questions

Me and my boyfriend have been trying for a baby since May. Usually when I'm on my period it's 5 days long and medium to heavy flow. Last months period and this period have been very light lasting 3 days brown on the 3rd day light reddish pink on the first two. Both period were late as well. When me and my boyfriend would have sex while on my period before he would have blood on him afterwards now he doesn't have any blood at all on him. I took test last month and this month and got all negatives. Why is my period different now? Should I make an appointment with my obgyn?