How can I show him I have a personality?

I think we all go through this phase.
its easy to talk to him when you have an audience. But when its one-on-one it gets really hard doesn't it? Your cheeks get flushed, your mind freezes and you can't think of ANY thing to say, not even something stupid? I'm the same way. Exactly.
i think that the only way to get over it is to practice.

{think about things you can potentially talk about before you talk to him, }

{talk to other people all the time, make a mental note of what works and what doesn't}

{and even if its hard and you feel like running out of the room with your head down, stop take a deep breath, and think to yourself "i am a funny, unique, smart person, I will not be intimidated (sorry spelling wrong) by him, no matter how much I like him," or something positive along those lines. }

You'll grow out of this phase, it just may take some time and patience.