Hey Eva, I sleep on my tummy all the time and never get blocked ducts.
I guess you will want to be careful if you've dropped feeds recently but if your supply was low anyway there shouldn't be a problem.
I would think you would be able to feel any blockages and/or chills if you get any.
Now that M is 10mo I think you're well outside blocked duct zone! Lol
PS: missing you on the 10-12month board!