Sadly, if your mom puts her foot down then you'll have to be respectful of her wishes and then when you get older you can get back into jumping if you still want to. That's what I had to do. I rode when I was younger and the second I started jumping my mom made me quit. She had seen my aunt get severely injured so many times and she was just too over protective. So I had to quit. I had to wait until I was out of college and could afford to start riding again. I had to wait a long time but I started back in my mid-twenties. If she's footing the bill then she has quite a bit of say. Just being able to ride in any discipline is a huge privilege. Enjoy it and take comfort in the fact that with all of the dressage background that you are building up, you'll have an advantage over others when you do get a chance to start jumping.