I feel everyone's pain here. The sizing for ABDL stuff isn't really all that great. And to top it off a lot of pants and shirts are cut so short it makes them uncomfortable. It sounds like being a vienna sausage (y'all) is about as fun as being a toothpick (me).
If you want to get a good fitting onesie from ODU or LFB what you need to pay attention to is the length. The chest, waist and hip measurements are just a ballpark figure for minimums. They will stretch much farther than the high end of what is stated.
To measure you will need a tailors tape like
this one. Wear the diaper you would normally wear and hold one end of the tape in the middle of your crotch and hold the other end at the top of your shoulder. Make sure you stand up nice and straight. You would then order the onesie that measurement falls in between. Then use the size chart from ODU to get your size. Both brands are cut and will stretch about the same.
For example, ABDElsa, being 50" x 50" x 50" and 5' 10" would put your shoulder to crotch measurement around 36" to 38". If that's the correct measurement and you want a nice snug onesie go for the 3X. Maybe even 2X. For something that is form fitting but not as snug get a 4X. If you want to try the LFB diapers get a sample from a third party site. Even if they don't fit you could always add an extender using the wings from another diaper.