Are you still in dance? What I found as a dancer/gymnast is while they do complement each other, gym can hurt ballet at higher levels. I mean concurrent higher levels. As a recreational gymnast through L5, and pointe for 4 hours a week I had no issues with mixing the two. Around L6 and 7 hours a week in pointe my dance teachers were complaining, until they finally told me I couldn't do advanced pointe anymore if I was in gymnastics. My gym coaches never had a problem with ballet though. Beginning and intro intermediate I never had problems combining the two. Body shapes for a gymnast conflicted too much with classical ballet lines is what I was told. A square hip in gymnastics is awesome, a square hip for a high arabesque will get you an earful! It gets really hard to reconcile the two at high levels, and you start thinking you're losing skills in both, when really you're doing ballet as a gymnast and vice versa. If you start having issues with a skill you already know, have someone watch you and make sure you aren't dancing through it rather than being a gymnast. A lot of times it can be a quick fix so never be afraid to ask for a pair of eyes on you.
Where I had issues in gym was learning how to stomp a vault board hard, and some minor power stuff that was worked out. I had fast twitch for days, but had to train hard for the power to back it up. Endurance wasn't ever an issue. Strength....was complicated. I was strong, I had defined arms. I never got the ripped arms of my team mates though. Nor the ripped legs for that matter. I did get the shoulders and back muscles though. A lot of times I was judged as weak unfairly I think, I just didn't know it at that age and did as I was told. My bar coach especially conditioned me HARD, and I did what I was told, never once thinking "hey I can do everything the other girls can, and I get good scores, why am I the only one conditioning 15 min longer each event instead of doing skills?" I just looked 'weak'. The reality is that I spent so long in dance my muscles had lengthened to a point where they weren't ever going to look like everyone elses no matter how many chin ups and bar routines I did. When I describe my training to my boss/elite coach, he dies on the inside, so he says. Do your strength training, but never judge your strength based only on how you look. Factor in the skills you can do too.
Where things will probably go well for you is on beam and floor. You know how to point toes and lock your knees, and how to spot as a dancer. Movements generally look graceful and purposeful will less effort. Being aware of where you are on the floor easily, and not having to look at your feet on beam are big pluses. I value spotting as the greatest single boost to dance brought to gymnastics. I never felt lost in the air or on the floor for that matter, questioned where I was being told to look, and got to work skills while all the other girls were learning how to spot full turns and such. Already knowing how to work performance space in dance really helps on floor where there are boundaries.
Chin ups really help.
not over a short time span though, did dance for many years and gym for many years. Ballet can be really helpful to gymnastics for flexibility and grace. I have been pushing trying to have a ballet for gymnasts class at my gym. How I wish those girls would turn their feet out slightly on beam and use a plie! I actually imagine after some time these girls are going to hurt themselves, you can't land straight legged and you will roll over your ankel if you come down on it wrong with your foot turned in. I never could get over the gymnast shoulder thing though and through out my ballet career it was a constant problem, coupled with the fact that I have wide set boxy shoulders 
Gymnastics is more about quickness and tightness, rather than flow and lightness. If that makes any sence. I don't know if any of that helped.
