Each time I was pregnant, I was always testing up to a week before my period would have been due. It was tricky to tell that early for me as the cramps I got were always so similar to premenstrual period cramps that it really could have gone either way.
In hindsight it was easier to see the odd differences - for me 1st time I had a bad headache in the week leading up to the missed period, which was unusual for me. Cramps felt just like a period coming though.
Every other time, just a day or so before or right on the time I should have got my peroid was when my boobs would feel more inflated than premenstrually so that is definitely a give away sign for me too if you are close to 2 weeks past ovulation.
Proper morning sickness, which for me was also wanting to vomit at the smell of coffee (which normally I love), didn't really hit till I was 7 weeks pregnant.