Pregnancy test. Mean i am not pregnant?

Hello, I am 25 and sexually active. I have irregular periods. Last period i had was 49 days late. I generally have 33-45 days cycle. This time my period started on 31/01/2017 and ended on 5/02/2017. I got intimate with my partner on 9th feb. According to an app i use, i should be ovulationg on 23rd feb. On 20th feb i had brown discharge which continued till 26th. On 23rd feb i had mild cramps and headache which i have sometimes during ovulation. Now, i am not sure if i ovulated or had implantation bleeding. I did a home test for pregnancy on 21 and 22 which was negative. Today, i did beta hcg test. How reliable would this test be at this point of time. We used protection. If this test comes negative then does that mean i am not pregnant?