Have you actually asked your parents about your own horse yet? I'm sure they know that you want your own horse eventually, but from what I've read (and I could have misunderstood) have you told them, "Mom, Dad, I think it is time for my own horse"? Find out about costs. If you think your family can afford it, and it turns out they can, I agree with with budget sheets and something well thought-out. If you have been leasing for such a long time, they may be more open to the idea than you think.
Also consider what barn you are at. Where in California are you? I'm also in California, and depending on what part of the state you live in, I might be able to help you find a cheaper boarding place and/or lease.
For the record, I understand where you are coming from. I used to ride 2-3 times a week for free (my trainer needed help with the horses while she was laid up with an injury) and I fell in love with my horse. I worked with her for a few years prior, but the more I worked her, the more I loved her. Only another girl leased 2 days a week and every now and then she'd be used in a lesson or taken out. I couldn't stand it. I bought her this past March and it was the best decesion I ever made. I couldn't be happier knowing I have her all to myself. While I now have to pay to ride, technically (paying board/feed/ etc) it is worth it to be able to make every decesion about my horse myself-how she is trained, what she is trained in, how to discipline her, who can ride her and when, etc. We have been jumping lately. I jump 1-3 times a week, BUT I don't jump alot. Like seriously, we will maybe actually go over a jump 4-5 times total in a single ride. Typically the 1/wk rule stands, and some weeks I don't jump at all. So far this week she has only been jumped literally one time. I jumped her over a 2' cross rail on Tuesday, and we have only done flat work since. Sundays tend to be "jump days" when we focus mostly on that.
That was all kind of off topic, haha. But yeah.
~He knows when you're happy
~He knows when you're comfortable
~And he always knows when you have carrots.