Okay, so I've liked this girl for the past few years, but haven't really realized it until recently. She knows me and typically laughs at a lot of the things I say, yet I'm not 100% sure she likes me the same way I like her. We're both Christians and both very strict on who we date. She hasn't ever had a boyfriend and I've never had a girlfriend.

Now I was thinking about asking her out, but I'm trying to figure out the best way. Should I just ask her out, or how? My plan was originally to wait until about May, then ask her to go to senior prom with me.
Any suggestions on how to tell if she actually likes me or how to ask her out?