Hi, I Have Been Oral Contraceptives For About 7 Years

Hi, I have been oral contraceptives for about 7 years now and I am 22 years old. My period used to be pretty heavy, 5 day period and I would have to change tampon regularly, and would leak through. For the past few months, my period has been quite a bit lighter, where I only would have to use 1 tampon a day. I take pregnancy tests once a month to make sure that is not why. This normal?