is the "tummy/breasts connection" inescapable? help!

I'm 50 yrs old, 5'5", 121 lbs which is "right" for my height & build.
Sorry to say, I've never been an exerciser :/ Until I hit my mid 40s, I
always had a flat stomach + small (34A) bust. Now all of a sudden in the
past couple of years I'm a 36B (yay!!) BUT to go with that, I look like
I did when I was 4 months pregnant, and I hate it. If I diet & exercise
down to 118, I lose the stomach but the New Improved Bust shrinks down
and sags, and my face as well - makes me look 10 yrs older .... Is there any way to "Lose the Lower & Keep the Upper"
or is it a case of either/or at my age? I'm really getting upset about
this. Anyone else experience the same?