Late period and early pregnancy symptoms, but negative test?

[Holl33]

Hi,
This is my first time posting on here, but I was just after advice from others that may have been in the same situation.

My period was due on Saturday, and still hasn't arrived. I'm now on day 35 of my cycle - which is normally 28/29 days.
I had low back pain and tight cramping on either 12th or 13th June, maybe both but can't quite remember. And was absolutely shattered Monday (13th) evening - to the point my hubby could hardly wake me!
Took an early pregnancy test on the 15th as I was too eager to wait. It nearly instantly showed a pink dot where the positive line should be, so I got a little excited but then read that it was probably just a faulty test!
Didn't think any more then till my period didn't show on Saturday. My breasts are quite sore (especially when I woke up this morning!) and although they're small anyway, they do look "fuller and rounder" if that makes sense.
I've also had cramps on and off every day since then, and yesterday and today have had aches high up just under the breast area.
The other thing that is a bit weird is that my hair has been soooo greasy this week. Usually only have to wash it every three days, but this week I've washed it and by the following morning it's oily again.
Took a test this afternoon, feeling quite sure it would be positive, and it was negative.
Is there a chance I could be pregnant and it just hasn't shown up yet? Or should it be picking up the pregnancy by now?

Just realised how long this is!! So sorry for the long read!