Is this desperate or not? Please help lol?

There’s a lesbian I’ve had two classes with in the past. The first class I wasn’t interested because I had a boyfriend ( I’m bi ) but I was walking into class one day up to my seat and caught her staring at me with her mouth slightly open and it looked like she wanted to say something but I looked away. We never did anything and the next semester we had another class. I caught her sneak a few glances at me throughout the semester and on the first day we did an ice breaker in class where we went around the class to say our names and she waited until after I introduced myself to the class to leave the class early which was weird because there were still more people that needed to go. She literally left right after I went. Another class she shaved her hair off and when she took off her hat to show everyone she glanced at me first. That’s when I became interested in her. One class she sat next to me because her seat got taken and she seemed nervous and was fiddling with the bottom of her shoe and her keys but she also looked bored so I don't know lol. She didn’t talk to me. On one of the last days of classes our professor called my essay out and asked me to explain it. When I did the lesbian girl did a loud “mmm” because she was agreeing with me and I’ve never seen her do that with anyone before. Also once I got nervous when the professor called on me and started stuttering and the lesbian girl started giggling with her friend but it didn’t seem like it was in a rude way. We had to schedule appointments with the Professor and I made mine for a certain time and she scheduled her appointment for the time slot directly after mine.
It’s been about a year since then and I just graduated lol but I’ve been meeting people in her circle and someone asked if knew her the other day at a party. I wanna just add her on Snapchat and was thinking I could say we had mutual friends and have had a couple classes but I don’t wanna sound desperate. Should I add her on snap?
Is this desperate or not? Please help lol?
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