Could I be pregnant?

Hi everyone so I have been trying to conceive for about 3 months now and failed every time I'm only 21 years old and been with my boyfriend for 5 years! I am really confused as to what is happening to me my last menstrual was on may 28 lasted only 3 days I'm usually 6-7 days heavy to medium flow I was so dissapointed as I wasn't expecting AF to come me and my bf have sex almost everyday it would have been impossible for his sperm not to meet my egg ! I'm a 26-27 cycle I don't know when I ovulate ! Before he left to Texas for a business trip we had sex on the 10th of April and a few times more before that! I was expecting af day cycle day 27 and it didn't come cycle day 29 I spotted the whole day light pink and cramped really bad  and some brown I've never had spotting before ever in my life when AF comes she just comes bloodshot red ! But the next day cycle day 30 I had heavier bleedingand lots of pelvic and back discomfort and slighter pain. it still wasn't the normal super heavy flow I have but it was a lot I was on pantyliners the second day of heavy bleeding I had brown and red on my pantyliner and then again blood I bled for three days and then it was gone just dark brown once and went away also during the bleeding I had small blood clots not much happened like 3-4 times ! Could this have been heavy implantation bleeding? Throughout may 10th to may 18 I was having really bad headaches days in a row and back pain some nausea  here and there and very tired! Around cycle day 24 I had pelvic discomfort my whole right side felt sore slight pain! And also a point were my breast felt heavy kinda sore but had shooting pains through my nipples also now have small weird bumps on my nipples!  Could I be pregnant ? Most of those symptoms have faided ! I have also been having fluttering in my stomach and pelvic area my uterus as well felt it more a day or two after the bleeding!