Advice?

So me and my boyfriend are TTC. I have three children from a previous marriage. We want one of our own ya know? So we've been trying for about two months now and I've been super nauseous every morning. My doctor said it could be stress, but I'm not stressed. I have nothing to be stressed about. I keep getting negatives, but with all three of my other children I was miserably nauseous. So my question is am I just crazy? I looked up phantom pregnancy and could that be a real thing? I do wanna get pregnant with him, but it's no rush. I want it to happen on it's own time. Sorry for the long post lol. Thanks in advance!