Girl too embarrassed to be seen with me?

We're both in college, and I've had a crush on her for a while. We're close friends, we sit together, and we text a lot. But I feel like she's always embarrassed to be seen with me. She's really popular, while I'm the sort of guy who sits in the corner with a couple friends. I'm at the bottom when it comes to popularity.

-Anyway, for her birthday, I drew her a portrait, as I'm an artist and I'd like to think I'm really good at it.

I handed it to her when I saw her in class, she smiled and said she loved it, and she couldn't stop talking about it with me.

But then later that day, she uploads it to Facebook, but my signature was erased, and I wasn't mentioned at all. The next day, I jokingly ask her why she erased my name, but she stutters and says ''I'm afraid my dad

would think wrong, he's overprotective''.

-We were once hanging between classes. I asked her to sit with me in the cafeteria, but she declined saying ''I get claustrophobic inside''.

-She erases her texts with me every single day. She texts me first most of the time mind you, so I know I'm not some clingy b*stard she wants to forget.

-She has no problem hanging out with other guys. She's a flirt with them too.

What do you think I should do? Valentine's is coming up and I was thinking of asking her out, but whenever I think of her I just get angry, as no one deserves the treatment she's giving me.

Any advices?