Nerves

Hello everyone my name is april me and my husband been to get pregant for the longest still no luck for us well my cycle come on july 5th 2017 i went off on the 12th of july 2017 now i came on yesterday we had sex three days after my ovulation could this be my cycle coming on or implation bleeding im so confuse and sad how can i tell im pregant everytime i take a test it cames back negitive im scared to take another one and it cames back negitive again im trying to think positive its stressing me out badly i feel like i want to pull my hair out lately been having mood swings like crazy lately pleaseeeeeeeeeeee help