Hey so I'm 18 and have very long (7 full days) and heavy periods. This month my period was only 4 days and was heavy on the first day but was very light after that. When it stopped about a week later I started to get spotting. Could I possibly be pregnant?

Unlikely.

Irregular periods are normal for all women from time to time. It is the LACK of a period that indicates pregnancy, not a lighter one. While some women do continue having a period throughout pregnancy, it is not really that common.

Possibly you could be pregnant. This could be implantation bleeding. Wait until your next period is due and take a test. But its to early to tell. When is the last time you had sex?