I'm 13 years old and my birthday is in May so next month and I have been growing for a little bit and I am nervous I will be short. I was around 5'2" when I started having a growth spurt in September and I'm 5'5" right now. My mom is 5'5" and my dad is 6'3". I have a twin brother that is about two inches taller than me. My oldest sister that is 17 (almost 18) is 5'2" but on the other hand my second oldest sister is around 5'7" - 5'8". I have grown around half an inch/or inch a month.This normal?