Wow, that's an AMAZING feat, losing that kind of weight. No wonder you're a little wobbly right now. Your body is still trying to balance "ghost weight" and hasn't figured out how to handle itself. (That's as good an excuse as any, right?)

Buy some biking gloves. You'll be glad you did -- they'll protect your palms.

And don't give up. You can do it! If you need to, ask at the bike store if they offer lessons. I was looking at one of the Dallas LBSs and there was a testimonial from a woman who had never learned to ride a bike as a kid, and found someone at the bike store to give her private lessons. She was thrilled and is now biking like a champ!

You may just need another session or two with someone who can help you figure out what to do.