[M20] I missed all of the signs from [F21] a girl that I’m interested in, but realizing it 6 months later. ASDFGH what do I do??

Being the dense brickhead that I am, I think I missed all the signs from this girl that I really like. We're in the same friend group in college, and she would openly joke, saying things like "if only you were my boyfriend". Or this one night we were walking back to the dorms and she literally held my hand cuz she said hers were cold. At the time, I kept making excuses, not letting it get to my head that she possibly liked me. Now, I'm pretty sure those were all signs (…right?). But the real advice that I need is…

I'm realizing all of this now (6 months after the fact). How do I move forward with this? I still really like her, and now I can't stop thinking about her. Have people been in a similar situation (realizing a love interest after the matter)? In people's experience, how quickly do people move on from a love interest? I'm afraid I'm too late and will have to learn from this experience the hard way, but have also seen some great advice from this community.