Is my gilet one size too big?

I went to the Rapha store last year in London and tried both medium and large. I have a large ish chest and arms due to gym, and found medium too tight around my shoulders where the arm holes are. Bought this large off Vinted instead, and it feels nice and comfortable, but comparing it to other peoples fits etc, it seems like it’s too baggy? Am I over thinking it? I’m not racing so I don’t have to have that Pro super tight fit, but I don’t want to be unnecessarily flappy

by Novel-Blacksmith1351