I know I am pregnant ,but I go months without my period.How can I figure out how far long I am, since I have not found a doctor yet?

There are many things that happen during pregnancy that can help determine how far along you are. There's the fetal heartbeat, movement, and other things.

An ultrasound will help narrow it down.

You need to find a doctor.

Are you taking prenatal vitamins? If not, you should start asap.

I agree with Alty. Since you have irregular periods your best bet is to find a doctor and get an ultrasound done.