Honestly, you've been living in different states for awhile and you haven't mentioned that Mom has interfered with your ordered visitation.
I think you're also reading your ROFR incorrectly, because it specifically states that spending time with your mother does NOT constitute babysitting. Therefore, you could leave kiddo with your mother whenever you wish without the ROFR coming into play.
It is unlikely that you would gain primary custody based on Mom's pending relocation, unless you can prove that it will significantly interfere with visitation or unreasonably limit your time with the child. Since you only have 60 days/year, that's pretty easy to work out no matter where Mom lives. In fact, a standard long distance plan would afford you quite a bit MORE time than you have now.