Is it good to mesaage your crush randomly?

https://able2know.org/topic/426379-1

Hi. I asked almost a month ago about what was the best way to get a girlfriend in college, especially since I find it hard to socialize because of my autism. Since then, I have had some conversations with her over the past couple of weeks, however, they didn't last too long, but long enough. However, sometimes, most notably recently, I've came up to this girl and I just said hi, and did not know what I would say because I can get quite shy. Sadly, it's not like she's in college everyday either (I go every Monday Tuesday, Thursday and Friday, while she goes Monday, Tuesday and Wednesday), and a lot of the time I'm busy doing work, and at times when I want to come up to her, I just hesitate.

I'm thinking about maybe messaging the girl on the Facebook Messenger app, since we are friends on Facebook itself. I'm just wondering if that's okay, because I'm worrying that randomly messaging her will creep her out. Plus, I haven't yet told her about my disability, so she doesn't even know about my social problems.

If it's okay for me to send a message to her, how can I start?