SO and I going though a desert stage?

Me and my SO have been together for 4yrs. He just finished Med school and is now working full time during his Residency. I also have a full time job, but his takes a more mentally stressful toll that affects him physically (low sex drive). When he's stressed out or mentally distracted, we only have sex maybe 4 times per month (at the most). He's 34, so im not sure if its due to his age. We have moved to a new state together and we both gained a little weight (were no where near large sizes, but we have gained "love weight"). We use to have this amazing sexual chemistry and always wanting more from eachother. Lately I've been feeling like he's not that into it unless we do it doggy style quickly. I have a very high sex drive and it's killing me!!! I want to have sex that doesn't only take 10mins and also doesn't involve me with my back turned! He always has the orgasm due to going in that position all the time now and im stuck with not having one at all! I have "toys" to play with, but I crave him more! I also feel guilty after using them even though he knows I do (due to our sex life declining). I've initiated it and he goes along with it but I can't help to feel that I don't turn him on anymore. In certain positions it's almost like he gets soft quick (which he never use to). He says it's stress and it tends to affect that part of him as well and we've had a lot of conversations that makes him become defensive. Then I feel bad and keep my feelings about it to myself. I need help figuring out what I should do. Our life together is great and we love eachother very much, I just can't help missing that part of our intimacy that would bring so much fire to our relationship!!! Do any of the women here have this issue? Do you seem to be the one with the higher sex drive? What do you do? I don't want to crush his ego as men usually think they are the horny ones and this is not the case!!