Thing is... age is going to catch up with EVERYONE, and there isn't a way to escape it. Look at Diane Keaton, who is nearing 70 years old age:
I think she looks AWESOME for being in her sixties... but she still has wrinkles and I'm sure a head of grey hair underneath the brown. MOST SIXTY SIX YEAR OLD WOMEN DO NOT LOOK LIKE THIS. Chances are, you will be more wrinkly and saggier than her, and it's something you are going to have to live with. Even if you have tons of money to drop on plastic surgery, you're still not going to ever look "young" again.
From all of the threads about babies and breastfeeding, you sound VERY concerned about what people think about your appearance. Breast feeding is weird and only non-human animals should do it. Pregnancy gives you a huge belly and makes you unattractive.
I know you mentioned a handful of times that your boyfriend/fiance is controlling. Does he think pregnancy is disgusting? Is he concerned about the possibility of your body changing? Because if he IS, and this is a big reason why you don't want children, you should really consider leaving him. Someone who TRULY loves you doesn't care if you have a few extra stretch marks and some saggy skin. You're going to have it sooner or later, anyway.