3days late....too early to test?

Ashleigh
So I'm new to this app and I've been TTC for a little over a year. Back in March my doc put me on 500mg of Metformin as a first line of defense because it can help boost fertility.  My husband and I have been married 4.5 years and we are finally stable in our jobs.  Since I took out my implant contraceptive last January we have tried everything we can think of to conceive each month. I've changed our diet, exercised more regularly, used ovulation tests some months and not others.  
The problem I am facing is that my period hasn't regulated since I took out BC.  Some months it is only 28 days others it is close to 37 or even 40, I never know when it will hit.  I've taken tons of pregnancy tests since my other calendar app tells me when I should be starting based on past periods and I end up starting a day or two after a negative HPT. Today is day 38 in this months cycle. So I'm 3 days late based on my "app". I'm nervous to take another HPT and end up "wasting" the money but I really want to know if I am or not since we are leaving on a two week vacation tomorrow. What if I take it and it says negative but its too early to tell. Am I crazy for even thinking it is a possibility since it's only day 38?