Did I conceive ?

Okay so... My boyfriend and I whom been together for just over 5 years now are trying to conceive so I need a little advice. I'm suppose to get my period Friday Sept 15, but for the past week and a half I've been feeling a BIT different. The weird pregnancy sign that I have is my gums will randomly hurt when I care for my teeth properly all the time also bleed sometimes when I brush them. Other symptoms are really tired, roller coaster of emotions and THEN sat Sept 9 I started spotting wasn't a lot at all and was pinkish, then Sunday Sept 10 spotted brownish woke up Monday nothing and since I haven't had any blood in sight but just feeling a bit off. Today is Sept 12 and I tested this morning and I got a negative test. What are the chances you lady's think i could have conceived with getting a negative 3 days before my expected period?