I havnt had a normal period and have sighns of pregnancy too

SO I was on Depo for 7 months then got off when my husband went to Afganastan hoping we would concieve but i have had weird periods I calculated my period and ovulation and my last period was on the 21 of December then he came home on the 4th i was to be fertile on the 5th or 6th then on the 8th i had a very very heavy period that lasted 4 days then he left to go back to afganastan on the 20th we had sex every day throught the two weeks he was home I was supposed to have a period on the 18th but no period I have takin two test both negative but im having symtons of pregnancy such as sore breasts felling tired could i still be pregnant? Help im going cray thinking about it