Is Light Bleeding Instead Of Menstruation Normal?

hi im 26 i have 3 children i am currently trying for my fourth in the past year i have had 3 biopsy on my uterus an scheduled for another on in a month i had my period 8/30 an ovulated 9/10-14th had sex on once on 9/10 an twice on the 11th since then i have had just about all of the signs of pregnancy nauseousness very tender breast headaces dizziness an pain in my lower belly an right side test say negative period came on 9/25th at first brown then dark red it usually last to days but is still on very light though can u tell me what may be wrong