Negative test :(

I just took a test (4days before period, so no missed period yet) it was negative and I'm heart broken. I had very light spotting on what would be my 7th day after ovulation so I really thought it was implantation bleeding and thought for sure it would be a positive test today..any thoughts? Should I keep testing everyday, or not waste my time and tests and just wait to see if my period comes naturally? Any advice is GREATLY appreciated!