Weight wise, absolutely not. She could carry a heavier rider. She also has plenty or barrel to take up your leg; your lower leg is in a good secure position on her barrel and you could even ride a hole or two shorter if you wanted to.
The only potential size mismatch I see is that your horse is very short coupled, and you are very long waisted, and carry a lot of your height from you hip to your head.
If you were jumping her, you would have to be very careful not to jump ahead or lean too much on her neck, as you could really unbalance her. If you were just learning to jump, I might want you on something with different comformation until you were secure in your position over fences.
But unless you're planning on showing in equitation over fences, I think you're fine.
Last edited by maura; 02-23-2012 at 12:51 PM.