I agree with almost all of the above, so I'll try not to rewrite what was already said.
I don't agree that you should hit uke with an atemi as Brian H. said, since you are both beginners and this can become personal. And the way you discribed him, he won't let you get away with it and you might get hurt- Badly!
Don't play around with atemi. It's important, yes, but it's NOT something to show your partner that you can get him if you want.
The other thing I didn't like is the feeling that all the advanced students seemed to run off and catch an advanced student to work with, leaving the new ones to themselves. I might be wrong but that's how it sounded in the original post. In our dojo usually new comers train with the more advaced students. It's not that they don't train between themselves, but first are the new comers. So one time an advanced will work with a new student and the next technique he will do with a friend while another advanced student works with the new one.
That way you can work with students that understand that you need to learn basics and have no cause to laugh at you when you don't succeed. More than that, they can tell you about your little successes along the way (your posture is much better, you are moving more fluently, good- you're not useing force, etc.)Aikido is not black or white, you get better all the time, and you should understand it that way.
I'm not a strong female, I'm 1.62 meters, and I know I'm doing better even when I face someone like your uke. So I didn't manage to throw him, ok, let's see why and how I can improve. Try to addapt a possitive attitude all the time, even when things are hard and you don't know what is wanted or expected of you. Getting angry will do the opposite.
I'm happy to hear that you are learning to control your temper. Aikido will do you alot of good for you in this. It did for me, especially since being a girl and not big I had a lot of times I was put down. Now I learned to smile at it and know in my heart that it doesn't matter.
People who are trying to show off, by proving themselves better than me are not worth my anger and I only smile at the silly fools they make of themselves.
Aikido takes a life time to learn, you get better along the way, both in technique and in your personal life. There are hard times, breaking points etc, but keep what you hope to achive infront of you and work towards it, even if sometimes things will go hard. Because in other times they will also go smooth.
I guess I'm blabering too much
So I hope you continue to enjoy training!