Wetsuit fit is a matter of give and take and not all wetsuit manfucaturer's sizing is the same. Unless you fit right inside the measurements, your're going to have to find the combination that is cloest to you. Never go smaller in the waist, that's always been the worst mistake first-time buyer make. You want a wetsuit to be snug, wetsuits aren't easy to get into - so keep that in mind.
O'Neill Wetsuits fits a person with boarder shoulders and stockier body types better than most other wetsuits - I call it the rugby/football/weightlifter build. Your BMI isn't representative of your height or athletic ability, you're the person people call when they need to move and want help to carry a sofa.
RipCurl Wetsuits fits a slender build much better, If there's less than an 8 inch difference from your chest to waist, based on size large, Rip Curl is probably your way to go. Rip Curl wetsuits tend to fit people who are tall for their weight. Some clothing seems a bit 'short' to you, if that's true, you a a good candidate for Rip Curl
Quiksilver Wetsuits seems to fit slender bodies and legs with larger shoulders, but not as broad as O'Neill barnds, more of a swimmer's build, you probably are in great shape and most clothing fits you very well. You wear the same size shirt in every brand, you have a 6-8+ inch waist to chest ratio and can wear skinny jeans.
There's a lot of information in this table, so read over it carefully. Using a tape measure helps a lot. And measure your waist about 1 inch below your belly button.
If you need help, call 877-560-9009 and ask for Angelo or Phil, we will be glad to help make sure you get a proper fit, we have over 30 years of combined wetsuit experience.