Hi there! I breastfed for 14 months and I have to say, try it. You won't now unless you try. I had a similar attitude as you do as far as not knowing if it was for me, what it would be like etc. It turned out to be so gratifying and amazing that it was one of my most proudest accomplishments. Now, as far as how it feels, I'm not gonna lie, in the beginning it was a bit uncomfortable, but the pain wore away fast, and before I knew it I never felt a thing again.
My breasts certainly aren't the same, I was a B cup before getting pregnant, a D during pregnancy,a D when nursing and back to a B when I was done nursing. They technically fit in the same bras, but they were kind of empty, not full like they were before. BUT, I would have no idea of knowing if that was due to being pregnant, or nursing. I have friends that NEVER nursed that said their breasts were much different after having the baby, so I'm not sure if nursing only will give you saggy boobs. I consider it worth while, like a battle wound of motherhood. Defintielt don't base your opinions or decisions on what people on a chat room will say, you have to decide for yourself. I suggest trying it at first, if you don't like it, then stop! You may surprise yourself, good luck!