Try on different wetsuit brands. As much as I want to fit into them, I can't seem to get the fit I want with Rip Curl wetsuits. I tend to find O'Neills that fit me nicely--I dunno why. I've had bad luck fitting into Excel wetsuits as well. Sometimes you have to be persistent and keep trying them on. Vary the sizes you try on as well, I tried on a 2XL and discovered, to my surprise, that it fit. Throw out the sizing guidelines you read and rely on how it feels to you, but try to imagine what a particular wetsuit fit would be like in the water. Your suit doesn't necessarily need to be skin tight. I prefer my wetsuits a lot looser than the manufacturer's recommend, mainly because I wear a hood shirt underneath my wetsuit when it's really cold. I also prefer my wetsuits to have a lot of play in the shoulders. Think carefully about your fit and you'll refine what works for you over time

Unfortunately, it may take one or two wetsuits to get it dialed in. Another thing with me, I don't order wetsuits online. I only buy wetsuits that I can try on and then buy. I'm too picky to hope I get the right fit from an online retailer.