Have patience Matthew,
I'm just about as new as you :P I start aikido two and half months ago. I can't back roll for the life of me. My front rolls need work as well. That's the beauty of Aikido- it forces us to slow down and listen to our bodies. Push your self to hard and you'll end up with shoulder injuries ( I should know.. I had to sit out for an hour and half on Saturday after biffing a forward roll!). The best advice I can give you is to have fun, laugh at your self. You're sitting at the bottom of Aikido's Paradox of the Kyu(ess):
You Don't want your Kyu , but everyone else does.
Enjoy your mistakes, leave your regrets behind. We're all beginners on the mat J