Lighter than normal and irregular periods?

[ofroyal]

Im 18 years old and I have started my period at the age of 12. I can't say my periods has ever been regular, about 4 months I would get them on dates that are located around the same area, then suddenly I would get it every 20 days for a few months, sometimes I would miss a month or two, etc. (The most regular it has ever gotten is at the most a year, then it went irregular again) I have never been sexually active (intercourse or anything involving an erection/sperm near my genitals -- I am a virgin). Recently though my periods has been at its worst state, since december, I have had my periods about 3-4 times. Right now, it's been about 3 months since the last period and I finally got them, however I really don't know if it's actually period because there is BARELY any blood or barely any pain (Usually when I get my period, I get a looooot of blood) Also, my period has always been around 7-8 days but the last few times I got my period it only lasted about 5 days. It always seem to lower in days. I'm really worried this could affect me having kids in the future? Lately I have been gaining weight and losing some weight on and off, I also have a very crappy mood (I might even have depression for all I know.) I don't think my diet is the cause here, I used to have my period even when I barely eat. Could anyone help me? I really hope this doesn't mean anything bad. :/

[FranciscaU]

You need to go see a gyno as soon as possible. Irregular periods are not common after two years post first menstruation.
Anorexia can cause irregular menstration. Weight gain is more associated with hormones. The following are two possible and very common causes:
PCOS can cause irregular menstruation such as you described. If you gain weight easily, over all your abdomen, have a more masculine body (such as more of a straight waist or rounded torso), and are excessively hairy, you probably have this. This is easily diagnosed with blood work (check for FSH/LH levels and DHEA levels).
Endometriosis can cause you to have really long periods such as 7-8 days. Women with endo tend to have more estrogen. Therefore they have a more feminine body, such as huge chests and a small torso. Gaining weight is also easy with this disorder as estrogen increases fatty tissue production. This is a harder disorder to diagnose as surgery is the only true confirmation.

[arlandonbloom]

It could be stress, or it could be something going on with your ovaries or even thyroid. I would definitely go to the doctor to figure it out.

[thatquietgirl]

You should go see a gynecologist and get some tests done.  It's normal to be irregular when you first start, but six years later you need to get some help.  There could be some hormonal issues or something else going on leading to the irregularities.