Laura, another idea for you which I use religiously if I think overtraining or insufficient recovery may be a problem.
My RHR is generally between 37 & 39 but during intensive training periods it may hover around the 43/44 mark the day following a hard session. When that happens I'll do a very easy recovery run and know that the following day it'll be back under 40. Under no circumstances will I do any running if it hasn't dropped below 50.
Today, for example I did 5.4 miles at 7am, a tough weight session in the afternoon and was ready to go for another 5.4 mile run at 5pm, but my HR was too high. Had to wait until after 6pm before it had dropped below 50. If it hadn't I wouldn't have went out.
As for the recovery runs feeling too hard - don't use your HRM.
Another thing to be aware of is the fact that most of us are guilty of assuming that when our times are getting slower or our training seems less effective that we are overtrained. However, similar effects can be achieved by not training hard enough or not doing the correct workouts. It could be that a review of your training is required.