From your earlier description I don't think I would describe you as "borrowing capital". You're laboring upon someone else's capital, but it's not like they've lent it to you and you owe it back, and you pay part of your income from your labor with it to service that debt. You're just selling your labor.
Even if using your employer's tools did count as "borrowing capital", you've also suggested that you have possible means of income that would not require "borrowing" like that, which in my book would still leave you middle-class because you're not borrowing out of necessity, you're just choosing to. It's like the difference between someone who rents because that's their only option besides homelessness, and someone who could totally buy a house at any time but rents because it's more convenient for them or something. I'd call the latter definitely (at least) middle class, but the former definitely not.