Is shorter and less abundant menstruation during the use of contraceptive patches normal?

I have been using patches since June this year, all the time I had heavy menstruation as before I started contraception, but in November and now the period lasted 2-3 days, is it possible that the bleeding has just regulated or should I see a doctor? I thought I was pregnant, but I did two pregnancy tests with a three-week break and both came back negative (the last one I did a week and a half ago)