Look this is going to be my 3rd charator! The only gap i have issues with is going to quesh.. Every other planet, you can keep in range just by doing the odd warfront and space missions.
I don't do flash points, they take too long to get going, don't give anything in return at all.
Leveling is just too fast, to fanny around with instances and heroics.
I don't know if you're just doing like 2 quests per planet or what, but you should be outleveling each planet you go to by at least 2 levels.