Phentermine and your period?

So I recently started back on phentermine last Friday the 1st and my period showed up 2 days later as expected, but it was super light. Like to the point that no tampon was needed it went on like that for about 3 days. When I wiped it was just a faint discoloration. I looked on google and most women said it made them have heavier periods. Anyone experience anything like this?