What should I [20M] do about my crush [20 F] of the past year and a half from university?

I met this girl the first weekend of school my Freshman year. Now, in the second semester of my Sophomore year, I still have as big of a crush on her as I had went we first met. Out of the 4 semesters, we've coincidentally had a class together for 3 of them, so we've gotten to know each enough to where we can carry a decent conversation.

The only problem is that I have no idea how she feels about me. During our second semester, I once asked her to one of my Fraternity's cocktails, but she declined saying her family was coming in for the weekend. Normally I could assume right there that she wasn't interested, but I do know that she was actually busy with her family that weekend because she posted pictures with them on Instagram. Also, I may be misremembering, but I'm pretty sure later in the semester she mentioned something about she wished she could come by our house more often but she didn't have a real reason to go (she used to come by with 2-3 of her friends, but after her friends hooked-up up with other people there, they stopped coming to avoid any awkwardness).

Since then I kinda accepted not much was going to happen at that time, and I had a casual GF for a few months. I broke up with my ex about 2 months ago, and just last week my crush came to one of our cocktails with one of my brothers while I went stag. I didn't get to talk to her much that night because I had to deal with a few unwanted guests, and I also didn't want to ruin my brother's date with her.

A few days after the cocktail, I decided to text her just to catch up and also gauge her interest in me. She started out by only replying once every hour or so (with engaged responses), but after three days of texting she hasn't replied to my last message in 12 hours.

A girl that I'm friends with suggested that since she kept replying even if it was after a long period of time, it means that she hasn't written me off, but isn't exactly interested either. She also suggested I start snapchatting her occasionally to see if communication between us starts to pick up.

I would love to ask my crush to a cocktail soon, but I don't want to embarrass myself if I'm reading the situation wrong.

I guess my question is do I still have a chance with this girl, or should I stop carrying false hope? If I do have a chance, should I tell her how I feel now, or hold off until we're a bit closer?

tl;dr: I've really liked this girl for the past 1 1/2 years, but I'm not sure how she feels about me, if anything at all.