What's the best way to get phlegm up and out?

I am 21 weeks pregnant and am sick and have asthma, i had to go to the er 2 times and get breathing treatments which i am still doing at home with albuterol in a nubulizer and also an inhaler which all the doctors say is safe? But i can't get that phlegm up and i feel so congested in my chest with it. My doctors don't want me taking any over the counter or anything? What rae your suggestions???? Thank You!!