Don't stress about getting a professional wax, us beauty therapists see all shapes, sizes, people, etc. To us it's a slab of skin with hairs that need to be removed - that's it! We don't even take note of anything but the job at hand!
Our waxes are also a much better quality than supermarket wax, and there are different waxes for different hair/area's/skin types. For example, Titanium Dioxide is used in waxes for its soothing and calming properties, so most places will choose waxes specifically to benefit their clients.
Just call a few places and express your concerns, you'll figure it out quickly if they know what they are talking about!