I think inexperienced partners are probably more your difficulty than short ones. A shorter person giving a fully committed attack can really force you to use correct technique, as the 5' tall shodan in our dojo likes to demonstrate.
Newcomers can be frustrating to practice with, but if you let them know what's wrong you can hope for quick improvement. You could try saying "Please attack with commitment" if your dojo rules allow that. But really the best thing is to talk to sensei.
You probably can't vary the techniques you use in class, but if you are practicing outside of or between classes and worry that you are using force rather than technique, there are ways to work on that. Many techniques can be done one-handed and this makes them harder to force. Some can be done from kneeling, which makes them *really* hard to force (and removes any height advantage).
This week our sensei have been making us do ikkyo without the second, helping hand, and I've noticed that this gives the larger and taller nage considerable difficulty because they can no longer simply tip me over with that hand, but have to get the ikkyo right. (I am smaller and less strong than most of them, so it gives me even worse problems, but I'm working on that.)
Above all, have patience. No one set of training partners, and no one set of problems, will last forever.