Wa'alaikum assalam! Aih, fibroids during pregnancy can be worrying lah, but at 21 weeks the good news is usually they settle down as baby grows, a few of my preggy friends had them too and everything turned out fine. Best to follow up with your doc on what they say is safe for you specifically, since fibroids can be different for each person and your doctor knows your full situation. Take care of yourself, mama!