Thanks for the recommendation Cupieqt :)
I think privates with a gymnastics coach is your best bet, most cheer coaches prob wouldn't like to hear that you're training at another cheer gym, but gymnastics is a different story (no conflict of interests). Also gymnastics gyms usually have more equipment and spotting devices for tumbling than most cheer gyms (in my experience).
Besides that I would I would suggest you take a look at my handspring tutorial under the 'emotional training' section. Most people feel the best way to get over fear of tumbling is just to be spotted over and over but its really when you become more self reliant that the fear lessens. Try to do more drills on your own, work standing bridges, bridge kick overs, back walkovers, back limbers, even back rolls, just get comfortable with going backwards on your own. If your gym has a loose foam pit you can just practice falling back into it, if you have serious fear issues going backward that should get your heart pumping, learn to actually enjoy that feeling in this easy and safe way. Enjoying this feeling might seem impossible or strange but if you like roller coasters or theme park rides you already enjoy it, if not you can learn to with enough practice :]
Hope that helps, let me know if I can help some more.
Frank