I just passed my PPL (h)
I did it in the high 60s, the number of hours is not important being safe is,and it takes as long as it takes. Yes some people do it in 45 hours but I would be reluctant to get in a helicopter with them. It depends on your age and ability (sounds like you went solo quite early, so ability is less of a problem then) the younger you are the quicker you pick things up. But I am late 20s and it still took me the best part of 70 hours to learn, and be confident flying on my own.
Also depends on your instructor, and the type of helicopter you are learning on, an r22 will take a bit longer than a 300, also doing the course over a relatively short period with as few breaks as possible, is best.
Good luck you have a great deal of fun flying ahead of you.
Just make sure you don't let the ground exams hold you up.