I haven't had a period for four months. i had a negative blood test. im gaining weight, my breasts are swollen, and peeing alot. am i pregnant?

Unlikely: It is unlikely you are pregnant since you had negative blood tests. However, if you want to be 100% sure, you should visit the doctor to get a repeat blood test and/or to get an ultrasound, where they can directly visualize the uterus. You could have other hormonal problems causing your symptoms beside pregnancy.

Abn menstual period: You need to be determined if you are pregnant or not. A ultra sound could help, quantitative HCG lab test, after that, if pregnancy is negative, you could check with you dr. All related to hormones, pineal gland, thyroid, ovary.