What Cause Scanty And Short Menstruation After An Abortion?

Hello. I had an abortion 3 years ago (was into 9 wks), and ever since the surgery my period has gotten short in terms of length of days and a lot less in amount. I went from having periods for 7 days to 3-4 days, and amount of vaginal bleeding reduced to about 30% of what I normally had. Plus, the color of blood is turned to very dark - close to black on the pads (the fresh blood when I wipe in the restroom is dark red ). Do you think I m okay?