Having Regular period with 30 day cycle. But very short period. Bleeding 2 days & brownish spotting 2 days. Reason for short periods?? Am I fertile?

Short periods. There is nothing wrong with having a short, light period. People with heavy periods would happily trade places with you. If you are having regular cyclic periods then it sounds like you are ovulating. We can not draw any conclusions about your future fertility. There is not reason to think you would not be fertile.