When do I need test?

I keep having random light almost cramp type feelings in my cervix area. It's not painful but I can feel something happening. It doesn't feel like regular menstrual cramps. I'm two days late and my boobs are weird feeling, again not painful but different. I've tested and it shows it's negative. I'm wondering if it's too early or if it's the tests I have. I bought a bunch of the dip stick type tests through Amazon. Should I go buy one of the digital tests or give it more time? Any advice would be fantastic!