I don't think domination and submission automatically make it BDSM. I think if you let someone lift you under duress you are submitting to their desire to lift you and therefore there's an element of domination to them getting you to submit. You could also say that if someone wants to be lifted and they get you to lift them that you're submitting to their desire by lifting them. Now of course you don't do these sessions for free so maybe your customers are submitting by paying you.
Getting back to BDSM, if someone wants to be dominated so they submit to a dominatrix, is it really submission if they're getting what they want?