20yrs old. had a bby breastfeed for 2months no period in 7 month , now 3months with a period every 2days before a period i bleed. is that normal?

Yes: This is within the normal range. Pregnancy with or without subsequent breastfeeding is a significant extrinsic factor associated with transient irregular cycles. If it persists for more than 2-3 cycles, get it checked out. Although, many times, such irregularity can lasts longer.

Irregular periods: Irregular periods are one of the most common problems obgyns treat. If this is one time problem it usually resolves on its own. If this is a recurring problem you should be evaluated. Infections ; hormonal changes can cause spotting. If there is a concern for pregnancy then do a home pregnancy test . There are many options available to help regulate.