Unusually soft and large breast

Hi! I am combo feeding my baby (breastfed, pumping, 1 formula bottle a day) because unfortunately we’ve had many issues breastfeeding including tongue/lip tie, bad latch, low supply, you name it. :(

this morning I noticed my right breast is larger than usual and soft but when I pump or hand express I don’t get much out. Nursing baby isn’t making a difference either... I’m worried if I don’t properly drain my breast it will turn into mastitis again (I’ve already had it 2 times)

Anyone know what this could be/what to do?