confusion!

so for the past 3 months me and my partner habve been trying to have a baby, last month my period was unusually short only lasting 3 days and was very light as normally it is quite heavy. i googled this and thought it could possibly be implantation bleeding so i did a test and it came back negative. i read online to wait till the next period is due and see what happens. i am now 10 days late on my period so i did the test yesterday and it was negative again. i have never been late before, if anything i have been 1 or 2 days early so i dont quite understand why this is happening. ive heard some women can do 3 tests before it finally shows positive but i dont want to get my hopes up(and they are not cheap)as i did yesterday. i know its not been long since we first started trying and maybe im reading too much in to it but it seems like my body is telling me something but the tests are saying otherwise. has anyone has the same experiences?