5/4/3 wetsuit in Portugal

[faithinwater]

Hi..

I bought a wetsuit back in September, just walked into a surf shop in Newquay having no idea what I needed. Basically just got into surfing and was looking for a wetsuit which would work for me in Portugal (Lagos/Sagres area) for April - June and September - October, along with summer in the UK.
The guy got me in this 5/4/3 Roxy wetsuit which I'm pretty sure now is too thick. It's also soo tight, like I just put it on and my arms were aching most probably due to lack of blood supply lol! Hoping it will stretch/be better in the water, but not holding out that much hope. He was so sure that was the right size for me though (I'm borderline 4 and 6 in Roxy sizes according to their site and I have a 4).

Am I gonna be ok? I've got a surf week booked mid April in Lagos..
TIA