Maddy Williams I used a 3-step mounting block and the horse was only a few feet higher than me.
Don't feel desperate, you are aware of the problem and that's a good start!
Do you use something to mount? Personally I always use a mounting steps, it helps me a lot so that I don't hurt my horse's back. You can use a chair, a bench...
The higher it will be, the easier it will be to mount gently 🙂
It just comes down to practice OP. When the strength in your core and legs are built up, it will become a lot easier to sit down gently. For now, just make a conscious effort to try.