hi Emily! i rode professionally for 10 years, and taught for 15, so hope you don't mind if i put in my 2 cents' worth.
since you haven't jumped in so long and were riding green horses, you're doing the right thing by staying off their backs and not catching them in the mouth. it's true that your heel could be a bit deeper and your leg, in the first picture, a bit further forward, but those are changes that will occur naturally with continued work, especially lots of work without stirrups and gymnastics exercises while jumping. also make sure that you're looking ahead, not down, and that you keep your fingers closed on the reins (when you start jumping bigger it's easy to break a finger if they're open).
i hope you have a good trainer to work with - it's really worth finding the best coach you can afford! eventing is so much fun, i miss it :)