It's fine and there's nothing to worry about. Never be afraid or feel silly for asking either!
It takes a long time for you to get a normal cycling period. The hormones just need a chance to build up in your system as you grow into an adult. Just think of your period as something that develops just like your breasts. They don't just become big overnight. They take time to grow.
Another thing is that you may just be someone who is going to have a longer cycle than most, and if it is, you can thank your lucky stars for that