am I or am I not

So I have been getting sick on and off for the last couple of months. Because of how it comes and goes I keep thinking that I might just be pregnant, which we are trying for. However, every time I have taken a test it has come back negative. Now the nausea is terrible and I don't want to take another pregnancy test just to have to come back negative. I keep thinking that it was so easy to get pregnant with Monkey and Bub (which I got pregnant with both of them before I had really thought about even becoming pregnant) and now that I am actually trying to get pregnant I am finding that it isn't all the easy!