4 days late, negative test and endo

Danielle
Hi!
I'm new to this app so bear with me haha!
I am 21 and was diagnosed with endometriosis 2 years ago and was told that as it progresses as I get older, my chances of having children may decrease. I have been in contact with dr geof shed in the USA who has supported this and even told me my chances are most likely reduced substantially already although it's minor.
My partner and I have been together for 5 years and bought our house 2 years ago, so we decided that the time was right and that I would stop taking my pill, in which I did in June this year.
My periods returned straight away and I have been like clockwork every 28 days for the past 3 months but now this month...I'm 4 days late.
Naturally I got excited and took a test, it was a clear blue weeks indicator one and it was negative. Obviously I'm a little down about it and am holding onto the hope that it's just too early to test.
What do you guys think and what are your experiences with endometriosis?