Breastfeeding and negative pregnancy test but feel pregnant? Missed period?

​I'm nursing my 14 month old about 3-4 times a day. I started having my cycles again in June then July and August today is day 36 and I haven't had a cycle for September. I def feel pregnant my breasts hurt way more than usual. I took a test this morning but it was negative is there still a possibility that I am still pregnant just too early? My last cycle was August 22-26. Before that was July 19-23 and before than June 1-5