Prenatal vitamins...

So I started taking them when we decided to TTC. Is it possible to have side effects enough so that they are mistakable for pregnancy? Nausea, bloating, upset tummy are all side effects. But I had previously (as a teen) taken them as they help your skin, hair and nails but experienced no side effects. I just keep thinking that these signs I'm having are not pregnancy. Maybe I'm just looking for a way to soften the blow when I get another BFN. I've also had headaches, giant overnight boobs and I've been emotional. Has anyone else taken prenatals before pregnancy? Did you have symptoms?