S.F.
Completely normal! I was from age 15 on exactly a 28 day cycle, unless under major stress, but I could plan my life around it- and I did. But- after our first son, the cycles became longer and were irregular until I got pregnant a few months later. Now I have stopped breastfeeding sweet number 2 about 4 months ago, and my cycles have fluctuated between 28-35 days. I am guessing it took about a year to get me here, and it's probably going to take a year to get me back to my normal rhythm!
All the best,
S.