Is it possible to be pregnant and not know?

I can add symptoms and answer any questions in updates...

Small update:

So the last time I had (unprotected) sex with my ex was April 9th, and the following period was on April 27th. Since a week or so before Christmas, I've been crazy stressed and my depression worse. On the 16th I went to a clinic for a test and it came negative and tested again with the same result on the 27th. But from the 8th of April to the first few days of May I had a lot of signs of pregnancy. Just recently I've put on a lot of weight for no reason which lead me to wonder the possibility of the tests being wrong... And what to do...