AntiM Antibody Detected

Samantha
Hey everyone,
So... I had my first OBS appointment this morning. Not only did I get bombarded with hundreds of brochures, booklets and 'do's' and 'dont's', I was informed that I have the Anti M antibody and it's rare, but doesn't matter?
So me being me, I've stressed about it all day, and eventually had to google it to get more info. But I don't really understand how something so rare can be insignificant and it all depends on igm? 
Has anyone had this properly explained to them and can dumb it down for me?
Also... I heard my little Dib's heart beat for the first time!!! I cried my eyes out!! So happy that everything is ok in that area!