I was 22 when I had my first baby...and I lost the weight from having her in the first year and a half, and was at goal. With my second child, a couple of years later, it took longer-about 3 years total to get where I wanted to be.
My third baby (going to be 2 next month) was a surprise...we had not planned on having more kids, and the weight from him has been the hardest to get off. I am still trying! I have lost some of the weight, but it has been much slower, and requires more effort. I am 10 years older than I was when I was trying to lose from baby #1, and that paired with it being the third time around has taken it's toll.
I am still plugging along, though. I know that I will get to goal one day, whether it be 2 months from now, or 2 years from now...so I'll take it.

I just can't get discouraged with trying to lose by a certain date, etc.