Nervous about riding today? advice?

I've been riding this one horse, prince. I show him in hunter division. He tried bucking me off after a 2ft jump a couple of months ago in my lesson, he did it twice. I thought he was just being feisty. Then he was lame and wasn't able to be ridden so I was riding another horse. At my next show I rode Prince, and he once again tried bucking me off. I don't know if he just tried bucking me off because he hadn't been out yet since being lame, this was his first time with some one riding him in weeks. But he scared me to death because he's huge and strong, and I'm a skinny girl with great leg muscle but my arm muscle isn't so great!!! It's not like i haven't fallen off before, I have plenty of times I just feel uncomfortable riding him, I don't want him doing it again. I'm riding him today...help?