Irregular period?

[CelticSoul]

My period is usually pretty regular. Not perfect, but it usually starts every 24-28 days after the last one ended. However my last three periods have all been irregular. Last month my period came six days late and when it did finally start it was lighter than usual. Then, only 16 days after end of the previous I started again with regular flow. Now, only 9 days after that I started again. The first day was very light and watery but today was a regular flow for the start of a period.
The only explanations I can think of are a) the months of May and June were quite stressful so maybe this is the aftermath of that and b) my period is trying to sync up with my female roommate who told me her period started the same day as the one I'm on now (yesterday). But I don't feel sick or have any other symptoms. I'm tired but that's from work and I feel a little nauseous but that's from the weather/stress over this issue.
Any ideas?
Thanks

[specialmom]

Hi there and welcome.  Well, this can always be so tricky to figure out.  yes, stress and changes in routine (and living arrangements as in a new roommate) can play a role in irregularity.  

question though, are you sexually active?  Any chance of pregnancy?

It might be a good time to go for a pelvic exam and pap smear.  That would be the best way to fully understand what is going on.  

good luck

[CelticSoul]

No, I'm not sexually active so no chance of pregnancy or an STI

[specialmom]

Okay, then see your doctor for a pelvic exam explaining this issue and they may check your thyroid and hormone levels.  They also sometimes will start a woman on the pill to regulate her.  But this is best discussed with your doctor.  good luck