What Could Cause Menstrual Irregularity?

i have missed my period for December and now January and have not recieved Feb. yet..i have taken a pregnancy test two weeks after my missed period in December and seen a doctor in January and she made me take a pregnancy test and she it came out negative...I have not been concerned because I have been a little more stressed than usual-me and my husband are newly weds and do not use protection..My concern is now that I may be pregant and that would be amazing but when I use the restroom and go pee only when I wipe am seeing a pinkish-redish slimyness it is hard to explain. can you help me