Pregnancy and fifths

So I am about 4-7 weeks pregnant. My toddler most likely has fifths (MIL is a RN). And my mom doesnt think I have had it as a kid, but she isnt sure. I've read some posts on here and am freaking out.

What happens if I'm not immune Nd I have it?? Am I high risk? What do they do? Just monitor?! My first appt isnt even until I'm 11 weeks (4more weeks) but I am going to the dr tomorrow for us both. Just wanna know some experience stories...