Anne, if when you are naked or just wearing a tight top you clearly have a waist, then I have to say it is the *clothing* that is the issue - NOT your body!
I think many many women have this issue, because off-the-rack clothing is made to fit the "average" figure .... which means it really fits nobody, because we're all unique.
And I understand that experience completely - long sharing Maya's frustration with jeans, until I found "my" brand - the one that works for me. (I did not wear jeans for oh.... 20 years... despite trying on brand after brand after brand).
And then we have Tanya there - fretting about saddlebags because one brand of jeans gave her whiskers - when we all know that that Tanya has a perfectly lovely figure. It's not her body - it's the CLOTHES.
Frankly I think there is nothing weird about my body when I assess it naked - well, except for the expected aging saggy bits - I mean the contours. I see a waist too. Even though yes, after two kids my waist is never going to get back down to 23 inches. (I think things internally shift and muscles can get so damaged not even all the sit-ups in the world can fix it ... that's what my OB/GYN claims, anyway... )
Despite looking fine naked, when I put on ill-fitting clothes - especially the wrong jeans - I look all goofy!! I look fat and puffy and appleish, with no butt, etc. Or if I try on the wrong size/style top, I look stunted and out of proportion and 20 lbs heavier etc.
You have a longer torso than I do so I don't feel qualified to give any specific advice about clothing brands or styles to try, but just wanted to say to be persistent and picky and keep trying things on until you find what works for you. Or pay a tailor to make something average fit you perfectly.
The swimming thing? Understand that too: both my kids are on swim team. Eldest DD is such a classic pear, the swimming just makes her upper body look tinier - delicate yet strong and lean.
But youngest DD is built more like me. Actually to be specific - she has a build that would be perfect for gymnastics; they wanted her to enroll in a program back in grade school because they saw great potential - but I nixed it because I found the training schedule all worrisome for a grade schooler.... but I digress...
She has stronger inverted triangle tendencies than I do. Swimming gives her shoulders and back an even stronger line. During swim season, her waist "shrinks" - but it's an illusion - it shrinks because her shoulders get broader and it creates more of a inverted triangle.
So that is one other thought: when the baby is a little older, perhaps enroll them in swimming lessons and you can get some laps in yourself? If the waist is not going to shrink, you can still build back up your upper body so that it looks proportionately smaller.