Hi,
I would say to use a larger between. I have been handquilting for about 20 years, and still use a 7 between. I struggled for years with a 10 or even a 12, but found the 7... It brought me back to handquilting and I still can get 8 stitches to the inch.
Use a gentle rocking motion-up, down, right back up, down, right back up, across the length of the design. It takes lots of practice but you can do it. It is something that helps me to relax in the evening. I don't use hoops; I prefer to heavily baste the quilt sandwich and the sit with the quilt in my lap.
Hope this helps.
Anita