irregular

so I started my period when I was 12 and, ever since then my cycle has been irregular, one time I didn't start for 6 months and also my cramps get so bad I can't get out of bed or move. when I'm at school I'll randomly get bad cramps to the point where I'm crying (no I am not sexually active whatsoever) well I just got my period today but the thing is, is my last period was in April and I'm now just starting. considering I'm 17 I don't think this is normal and neither does my doc. what do y'all think?