I need help on my next step in asking a girl out

I need help proceeding with asking a girl out

I need help with my love life. So last week, I (19M) met a girl at my school’s weekly free bowling night. We got talking and my roommate seemed to think that she was into me. I was totally flirting with her the whole time. I may have missed my chance to get her number that night, but tonight was bowling night again. I went to bowling early, told the owner to the bowling alley to put us next to each other on the lanes so we could talk because he knows all the students. Well that didn’t happen and the guy ended up turning disco lights and loud music on, so the few times I tried to go over and talk to her when she was on the other side of the room, it didn’t feel right and I got nervous. I did talk to her for a few minutes and I think I made it quite obvious I was into her, as my roommate and I kept seeing her look across the room at me after I had gone over to talk to her. Im 19 and I have never asked a girl out. We talked for a couple minutes tonight and I left. I don’t know what to do now. I can’t wait until next week at bowling because this has been eating me alive for the past week and I can’t deal with my brain tormenting me for another week. Do I send her an email saying my feelings? Do I put a note on her door? Do I bite the bullet, suffer another week and ask her next week? Help me please. I haven’t been happy in years and I feel if this goes right, it could turn everything around for me. I need your help, as Im suffering here. Been lonely forever and something has to give.