Most Helpful Girl
I think if you want to show her you're interested then you should flirt with her subtly first, let her know you have feelings with her without out rightly saying it at first. But that would just be my preference if I had a guy like me that was in the same position as you are.
Don't worry about looking like a "coward" by asking someone out on a date over the phone though, girls don't see it that way at all. It doesn't have to be some big gesture. Just do it as you feel most comfortable.
Most Helpful Guy
Why is your relationship status set as "dating"? Did you manage to get a date from her?
Anyways, first, find out when, what time and where her last final is. To find out where is her last final, ask for her course and section number, and depending on the college you are studying in, you can look up the exam room and building she will be in.
On her last final, you can wait for her (without getting detected) near the building/room she has examination in. When she exits the room, pretend that you bumped into her. Then do a small talk, around 2-3 minutes, then ask her out on a date and see what happens. The problem with this is, if you failed to intercept her (especially the case if she exit the exam room EARLY), you are dead. You can bring a friend to wait outside the door and signal you once she exit the building.
I will strongly suggest you to ask her out when she have done all her finals so that she will not be overly pressured (Her finals already give her enough pressure, she does not need more.).
I am a kind of person who CANNOT ask by phone or text, but CAN ask in person. I find that the latter way is not as scary as I am able to get a response from her. She can ignore me if I ask by phone or text and that will give me heartaches.