Instead of focusing on what you "should" do (there are no shoulds in sex), have you considered having a frank conversation with your partners about what they enjoy in general, and what they enjoy with you? I think you might find that helpful.
The losing interest in sex with Glasses is its own issue, I think. You'll have to make a decision on how you want to handle that.
I did have a nice long conversation with Ponytail about all of this. I told him the 5 areas where I had been feeling inadequate and he was very reassuring. It helps to hear that from someone who has had sex with so many people.
And then last night I didn’t talk with Whiskers about *all* of my insecurities, but I did bring up the fact that that I really enjoy telling him how much I appreciate him — and that I would love it if he did the same. We had a good conversation and he explained that he avoids “tit for tat” compliments that feel in genuine. He acknowledged that he does have those kinds of thoughts and that he should should make an effort to text me when he does. It was a good conversation.
As for Glasses, I made a date with him for today. When we made plans I expressed to him that I want to reconnect with him physically. So I am hoping for some quality intimacy and maybe some good conversation about what we would both like to see develop in our sexual relationship.