4 days late, negative test.... first timer.... advice?

I have a fairly long cycle like 35 days and should have started my period Feb 28th. It's been 4 days now and I took a ClearBlue digital test yesterday and it was negative. I have more CM than anything and cant decide if I have super light cramping or if its all in my head. My boyfriend and I are serious but not excactly trying but would be happy either way. Im 26 and he is 27 so its not a bad time in our lives. Can't decide if maybe i just tested to early or maybe could have used a different/better test. Any thoughts from anyone?