Pregnancy symptoms?

This would be my third baby and you would think I would know but it’s been all different scenarios! Me and my husband are trying for a baby but we’re not totally trying to prevent it. I am on the mini pill but I let him cum in me as we don’t mind to have a baby but I am also on the mini pill to prevent it. However, Thursday and Friday of last week I got really nauseous out of nowhere and a headache. I’ve been tired lately too. Now today after eating lunch I just feel weird and nauseous. I’m tired and I don’t have any energy. I just want to lay down and chill out or sleep. I have no clue when I was last fertile or if I have been lately due to being on birth control. But I do know that birth control isn’t 100%. I can feel a headache coming on again. I work for a doctor’s office and am almost considering getting a blood test done but I don’t want it to be a waste. I test every now and then to be safe and about two or so weeks ago it was negative. What do you guys think?