so confused

Tasha

last period april 18th

ovulation was supposed to happen per app may 1-7.

went to the doc for something else on may 4th. they gave me a pregnancy test and it was negative.

I'm 18 days late now. thought it was from stress. took a test yesterday and it was positive.

my question is when did I ovulate? when did I get PG? its telling me I'm 7 weeks already. but wouldn't the may 4th test have come back positive if I were that far along??