Trying to get pregnant

My period end on the 7 day. So i try the ovulation strip in the morning till now day 11 and it shows negative. Feel sad . Last month i just randomly try to test the ovulation strip on day 15 it was positive but i did the deed day 16 but i was kinda down that i did not conceive. So now i wana keep track on ovulation day. 5 attempts still negative now. Mummies I might not know can help me so i dun feel sad. Thnx in advance