“Light period”

I take provera for the first 10 days of the month to have a regular cycle. (It’s actually 2-11 because I forget on the first) This is my 4th period while taking it and I always start 4 days after stopping provera (Day 15 of the month) like clockwork. The past three cycles have been fairly normal in terms of flow (what I had early menstruation/high school) but this month I had spotting the day before and this past Tuesday 4/15 would have been my for sure start date. While I did use a tampon I barely filled half of two (Started at 8am took out at noon, barely used but used another took out by 6pm same situation) by the end of day one. I have only used a pad since and it’s only when I wipe. It’s practically over now. My pregnancy tests are negative but could I still be pregnant and just need to test later? Partner and I are TTC but he has low numbers and we’re told IVF is our best option.