300 isn’t a huge implant and although ppl measure a E they won’t look that big, I had 450 n I fit a Ecup I’m 3weeks post op, if u look at my profile pic ur see they don’t look huge, my friend had 300 measures DD but without a bra looks about C, I’m sure your just worrying coz your nerves are kicking in,your surgeon would make you oook stupid and would tell u if that size was too big, try not to fixate on cup size but rather the look you want, which is im assuming a full breast that suits your frame and not the beach ball look xx