Help!

Ok yall. I have already been told it is very unlikely I will be able to become pregnant and have been looking into other options. However, I was supposed to start on Monday and it's Thursday. I am always very regular and have never been late. I have taken three pregnancy tests and all are negative. Do you think it might be possible to prove doctors and tests wrong? Is there a certain test I should try that might work better than others. Please help!!!