I Am 35 Years Old And For The Last 4

I am 35 years old and for the last 4 months I have felt I have gained weight but doesn't really show on the scale but only really gained 4 pounds in the last 3 months. I have been feeling tired lately and breasts seem sore and I munch a lot. Last time I had sex was Dec 15, 2015 and I thought it could be pregnancy as I feel I have a bloated belly. But I have taken a test on Jan 20 and came up negative and than again this morning and still negative but feel like the signs are there but if it comes up negative could it be that or something else. I am feeling a bit worried and just want to know as I don't want to be pregnant right now