I Am A 36 Yr Old Woman. I Have 4

I am a 36 yr old woman. I have 4 children. Yesterday I started to feel fluttering (as if quickening). I took a urine and serum pregnancy test. Both were negative. I have had somewhat regular menstrual cycles that have not stopped. Being pregnant 4 times in the past, I know that distinct feeling of having a baby move inside me. I am freaking out. I am worried I might be having a cryptic pregnancy. I also had low progesterone levels with my past pregnancy. I was wondering if somehow that could be affecting me in that I am still bleeding monthly and also getting negative results on pregnancy tests.