@john74,
Four months is really a short period of time.
Try to focus on how happy your daughter is when you are together.
izzythepush has given you good advice.
have you had a chance to speak to other parents in your area about what life with a small child is like? have you done reading on developmental stages of children?
you said earlier that your ex-wife is supportive of your time with your daughter. would she be willing to take your daughter out for you to meet with her at the park or in a restaurant?