When can i test?

Hi guys,

My boyfriend and i stopped taking birthcontrol because we are ttc. I was on the pill and had my period at the end of may. We thought, let's just stop taking it, and see what happens, no pressure. But after a week or 4, i keep having this pressure on my lower abdomen and i wake up feeling very exhausted. Makes me wonder if i could be pregnant (already).. but because i haven't had my first 'normal' period yet, i have no idea when i could test for the first time, without having to spend tons of money on pregnancy tests. Any of you have any tips?