Crazy thoughts during first trimester

I have had fears of Miscarrying ever since I found out I was pregnant. I have never experienced one & I didn't have these fears when I was pregnant with my son, but now I constantly am afraid of it. I check every time I pee if there is blood, I sit & worry about it when I lay in bed. Just constant fears of it. I don't know if maybe it has something to do with everything going so right as far as family being excited & boyfriend ready that I am just afraid something will go terribly wrong or what. Has anyone else experienced this?