Having some of the same issues myself, I’ve come to the conclusion that my saddle is simply too large. It’s difficult to see that it’s too big, so the default advice I’ve always received has been to just shorten my stirrups, which has been pretty counterproductive, to say the least.
So how do I know my saddle is too large? When my legs are in the correct position, namely, when I’m able to keep my weight balanced over my legs, there’s a good 1" gap between the block and my leg. Not to mention how I have to fight to keep my legs in that position in the first place. I’ve done plenty of good work in saddles that were too large for me (since I’m pretty sure I’ve always been in too-large saddles), but they were flatter or plainer or had stirrup bars further back or something that made it easier to stay balanced.
Not sure what size saddle you’re looking for, but it might be worth trying something smaller than you think you need. Of course, if you’re already looking for a 16", this could make life worse…