Hi there. Well, I'll tell you this. And this isn't what you want to hear. I have no qualms about breast augmentation surgery and believe women should do what makes them feel good. BUT, I'd wait to do it. Have your kids first. I have a friend who had implants done and what they don't tell you is this . . . first, they don't last forever. About 10 to 12 years and you have to redo (and who knows what your finances and time available for recovery is like 10 years from now and 10 years after that and 10 years after that . . .). Second. having a child absolutely changes breasts. This same friend found she was very misshaped after having her kids. Her breasts sagged over the implants so she has a lump at top with breast that falls under it. She says it is weird looking. (never have seen it but I'll take her word for it). In order to fix it, she has to have not only new implants but breast lifting. She can't afford it and with her kids, doesn't have time to do it anyway.
So, what she thought was cool in her 20's appears to be a maintenance issue for a lifetime. They never really talked about this stuff with her. Health magazine has an article out right now (maybe last months or this months issue) that talks about all of this. I was glad to see these facts women don't think about in print.
As to not menstruating, I think I'd try to find out why as that is a health issue going on most likely. Are you exercising or dieting too much? That can cause a lack of period. Thyroid issues can also cause very long cycles. in my late 20's, I had a slow thyroid or hypothyroidism and had periods every 3 to 4 months.
Anyway, I'm certainly not against implants! But I'd wait until you have your kiddos first (if you desire kids). good luck