Need Relationship Advice

I could use some advice. My girlfriend and I have been together for three and a half years and have lived together almost two years (since June of 2018). We are not yet engaged due to a variety of reasons, mostly my hesitation. I am 39 and will turn 40 in July. She turned 39 in January. With our ages, we should be married or at least engaged by now. I realized that, especially since she wants children. She and I have never been married before, and I was her first real boyfriend when we met (she was 35 then).

There is quite a bit of building animosity and tension from her. She wants to be engaged, and for good reason is concerned about being able to get pregnant after we are engaged, then married. I have become too comfortable in the relationship. We do love each other and are best friends. We both work long hours and have a lot in common. But there are a few things I cannot get past to take that next step. In March of 2019 we went and looked at engagement rings, I purchased one and have had it since July.

One other thing I did not mention is that we do not sleep together. When I had moved in with her, we had never spent the night at her house. We had spend the night at my place many time and at hotels, etc. We have a completely different taste in blankets, hot/cold in bed. She's always freezing, I am always hot. I have tried to sleep in there, but often I lie awake until 3 or 4am. We do have a spare bedroom where I sleep, and I am able to sleep normally in there. She is always asking me "when are we going to sleep together" or is upset why we aren't sleeping together, and telling me how weird it is. I know it is weird, and not normal. But I am unable to fall asleep, and when I stay up it keeps her up. I work long hours and I need to be able to get at least some sleep at night. This has been a major point of contention for us. Usually once a month or so we try again, and maybe I'll fall asleep and some nights I can't. I think this could be the cause of some of our intimacy problems. I never had a problem sleeping in bed overnight with a previous long term girlfriend. But, this is one more thing that she is on me about constantly and I feel awful that I can't fall asleep and be with her at night.
There are really three major things I cannot get past. The first is our religious backgrounds. She is Jewish and I am Christian. Obviously we knew this from day one and we were both accepting of this. But over the past few years it keeps becoming more obvious that she won't budge. I agreed a while back that if we were to have children I was fine raising them Jewish. This made her happy, but I also shared that I do not want to give up my upbringing. Since then, as we have discussed other things such as a wedding, it becomes more and more apparent that she won't work with me on this. For example, I was discussing what a wedding would look like, and she immediately stopped me and said "of course it has to be at night after sundown and we have to have a rabbi marry us, otherwise my parents won't go for that." What about what I want? I've never been to a nighttime wedding? That would be very odd for my family. I mentioned celebrating Christmas and how much I love that, and she said we could never have a Christmas tree because it would confuse our children. And, our child has to have a certain name because of tradition. What if I don't want to follow that tradition? There have been other things too, it just worries me that it will be all or nothing. You would think that in 3.5 years we would have worked this out but we haven't.

The other concern I have is our physical relationship. I was her first sexual partner, and I think probably her first kiss, all occurring at age 35 for her. I've been in relationships and have experience, and I wanted to go slowly so she would enjoy that part of our time together. After all the time we have been together, she does not have interest in sex and is unable to climax. When we are together in that way, it feels like she only does it for me. There is no mutual pleasure, it feels like only a release for me. We have tried books and even went to a sex therapist and a OB/GYN that specializes in dysfunction. My girlfriend takes 14-15 pills daily for migraine headaches, and I have often mentioned that I think it is all of the medication she takes that could cause the problem. We still have made no progress in the physical area and it has been very frustrating. I want to feel "wanted" like she needs me physically. She dresses very conservatively, and I've even asked if she would wear something fun, just to spice things up. She doesn't like to wear shorts, and wears long pants and sweaters even in the summertime. She doesn't masturbate or really even "think" sexually. This may seem petty, but I want to see her look good, she could be so sexy if she wanted to be. I am afraid she just isn't wired that way, especially at age 39.

My final major concern is her happiness. We do a lot for each other, especially now that we live together. I want to make her happy, and it is very difficult. She has a high stress job and works long hours. I do as well. She is always coming home upset about something, which I understand. I try to comfort her and help when I can. Maybe I am more of an optimistic person, but it scares me that her anxiety and unhappiness will never change. It swings back and forth. When things are really good with us, they're great. When she's stressed, it's not good at all.

I completely understand why she is pressuring me to get engaged as soon as possible. We should be, and that is 100% on me. I should have left with my concerns a year ago. But I love her, and she and I have so much invested. This week she found out she is a carrier for the BRCA 1 gene which can lead to breast, ovarian, and pancreatic cancer. She became unglued, saying that we should be married now so we can have children before she has to have a mastectomy and a hysterectomy. This makes me feel awful, because I think I have ruined her window to have children. She is at her wits end and wants a decision from me right now. I told her my concerns, and she doesn't share the concerns with me.

I know that this situation is my fault and that I have not made good choices along the way. However, I am in this situation. Does anyone have some advice to help me, or do I need to just propose so we can move things along. Thank you in advance!