Hello, It Is Going On Almost 3 Months Since I

Hello, it is going on almost 3 months since I last had my period. I am usually extremely regular and am on the pill but missed several days because of my dog getting ahold of my medicine. The 2 months prior to the first time I missed were both on time but shorter and lighter than usual. I didn't think anything of it till I missed my period; I took a test I already had and it came back negative. I have taken a couple more and all have come back negative. Over the last few months I have gained some weight and my clothes are all tight and some don't fit. I just chalked it up to sitting around and not being as active. I have also been extremely tired and get upset more grumpy than I usually am as well as I have been urinating more and have had more bowl movements than usual. Could I still be pregnant even though I have had multiple negative pregnancy tests.