so what's the question?

Tell me you "freaked out" and bailed without paying and that's your worry that you can't go and face her again
or what?  
If that's the case go back and tell her you forgot you had paid but not to worry you would never do anything like that and blah , blah, blah.  
Actually that happen to me at a local eating place here. I went back and pay. I actually had forgotten. But the guy said not to worry and the couple of times after that he was ready to charge me and stuff. But after a while he stopped worrying had more trust. Now he went out of business because of pandemic. What all this got to do with your question? I don't know.  
If you freaking out because you have feelings for her? Don't, have feelings of friendship, lust and trustworthiness if that's the word. Go back and keep going. Just don't tell her you love her or you'll mess everything up.

I think it's more complicated because we've seen each other so many times and slowly she's been slipping me the L word a couple of times but "not like that" or so she says but now Idk if we are more than friends or just customer and provider it's really hard looking at her like just a lover now that we've done so much together.

I only know the business side of it all.

Not cool that you freaked and bailed, but you can make it right by going back asap (and convenient for her) and paying her. If you really think you have more than a provider/client relationship, the test is asking her if you can have sex without a fee. TBH, I'm hoping you try that soon and she sets you straight. Not being cruel but it's for your own good. You can't stay in this limbo state for long because it's not good for you emotionally. Do a search on the discussion boards and see what others have had to say. You're not the first to think it might be developing into something more than just a business transaction, and from what I understand, in rare cases, it's actually happened where client and provider connect beyond the hobby, but I think it's a needle in a haystack. Sure it can be more than "just" business, but odds are it will still be a business transaction. Here's what I mean: I like my dentist, and I've run into him outside of the office and it's cool to see him. We have a good relationship and we talk about a lot of things. We genuinely like each other. But I would never dream of asking him to do a cleaning for free. (actually his dental hygienist does the cleaning but you know what I mean). Even though we like each other and have good chats, I'm still going there for a professional service and the guy is earning a living. I think it's the same with providers. When you're role-playing, sharing your most intimate fantasies, yeah man, that can create a real connection. But a connection most likely does not mean she's falling for you.  

Good luck and I wish the best for you and your ATF.

i have had a couple special ladies like that over time.   and we use the phrase "i love you" but what we are saying and we both clearly know this is  "i love what you do for me"    which isnt as easy to say while you are fucking each other's brains out  LOL  

so as long as you are aware of what you truly mean there is nothing wrong with saying "" I Love You  "".   and even the most jaded  pro likes knowing she is special to you.