need help.

so I had my baby six months ago,been breastfeeding since and never missed a period,it would last for about 4days or less.. the month of December I did not get my period at all and I threw up last Tuesday, my husband and I have been intimate and started off not using a condom and then used it or sometimes just the pull out method. sorry for giving to much info. I've taken pregnancy test but so far they are negative.. last night and this morning I've been having a light amount of brownish/red discharge... I wana know if anyone had gone through this... or what could be happening.. have an obgyn apt. on Monday.