What is wrong with me ?

Since I was 13 I've been getting these small puss filled pimples all over me.I am 18 year old female. I've been to the Dermatologist several times, been prescribe to different antibiotics but it still won't go away.I usually notice them more a week or so before and after my period.In January I got an abcess (abscess) so big I had to go to the emergency room after some days so they could remove it.I'm also prone to ingrown hairs.I used to get them under my arm when I shaved but since I started using a trimmer to shave under there it stopped.But i still get ingrown hairs in my private, even when I spend weeks without shaving I have ingrown hairs and boil like pimples.

I get the small pus filled pimples mostly on my leg,butt,and foot area and they also look like the acne I get on my face now and then.
I've taken blood tests and they were all normal except for one I took when I was about 14 and they said it was low.
I also feel light headed when i haven't eaten something sweet or awhile , so it might be my sugar.
I just cancelled my  appointment with my dermatologist for tuesday so I could research mor about this.I go there every year and I still don't get any help. I need to know what's going on so when i get there this time i could explain what's happening to me better.

Is any of these things related?