I started af on the 5th ended on the 8th, two days later I had a large amount of cm and mild cramps. My breasts have need hurting for 3 weeks now.
Could I be pregnant? I know it is too early to test but it is driving me crazy.

If you are having sex you could be pregnant. There is just no way to tell at this point and normally no signs.

You will have to wait and see if you miss the next period, and if you do, wait another 2 weeks to test.