Count yourself among the lucky few who aren’t hairy! This is fine. Some ethnic groups aren’t hairy at all and never get much in the way of body or pubic hair. Even if the rest of your family is laden with armpit hair, having none is not abnormal or a problem. As long as your period is happening, your hormones have matured and that’s all that matters from a long term standpoint. Be happy that you don’t have to shave and chances are your BO isn’t as bad either! I’m jealous!
I think the most important thing to remember is that we’re all different. You’ve started menstruating, so that tells me that your body is developing and hitting its puberty milestones just like it’s supposed to. For most girls, armpit hair starts to grow a little while after they get pubic hair. So, if you have some pubic hair (even if it’s scanty and soft) and you have your period, armpit hair may still be on its way. Then again, you may never have much armpit hair (and that’s not a bad thing). I know I have to shave my legs and underarms every time I take a shower. My sister, on the other hand, can go a good three months without having to shave. She’s just never had much leg or underarm hair and what she does have is fine and soft. Frankly, I’m a bit jealous of my sister -- I think she got the better deal!
Although when it comes to menstruation, nothing is “normal” this is really common. There’s no set of “period rules” that say first armpit hair then period, or vice versa. And in some cases women grow very little to no underarm hair at all. That’s just what’s normal for them. Some hairy divas, like myself, might even consider it lucky! Hope this helps!!