I'm 23 and have had very regular periods that are always on the heavier side but my last 2 have been very light what's going on? Can this be normal?

Yes. It can be normal, but it can be several other things as well. Some women can have light periods for several months after getting pregnant. If you recently have lost weight it might result in lighter periods. Sometimes thyroid disease can also be associated with change in menstrual flow. See your physician.