Once you've been examined and found nothing to worry about, you have no reason to panic. If you are very worried, you can see other specialists, but they will probably not say anything different from the previous ones. It is individual for each woman, but it is assumed that it should come to you within two years. I understand that you are worried and you want to be like your classmates, but each organism develops at a different rate. If they haven't found a health problem for you, then everything is fine and you just have to wait for the day.
1 yoursmolly answered
No, you have nothing to worry about. Don't worry :) you obviously have a slower development, up to 1-2 years if it doesn't come to you, then worry.