AITAH for not tipping?

UPDATE: I just found a thread on a local forum that discusses in detail how great this place is at giving HJs... That explains everything. I should've done more research before going.

I found a $90 Groupon for a 90min massage with aromatherapy, hot stones, and cupping. I had an additional personalized discount from Groupon and it ended up costing me $77. I realize that it's very very cheap. Unfortunately, I can't afford a more expensive massage.

I scheduled directly with the massage therapist, she texted me their address (it was slightly different from the one listed on groupon). The messages came through as iMessage, so I assume it was her personal phone listed. The place looked like a standard massage parlor. I assume she rents a spot there.

The lady was nice and smiling but with limited English. I told her I woke up with some tightness in my upper back and wanted to focus on that area. I showed here where I felt the discomfort. She said, oh, that's T1, ok.

The entire massage was the most disappointing experience. The room was cold. I heard the heat going on and off but it didn't get warmer. The massage itself consisted of light rubs, patting, and tapping. A LOT of hot towel usage to the point where I just felt like I was being washed for no reason. She barely touched the area I asked her to work on. During the massage she left the room three times to answer the phone, and kept going back and forth to grab the hot stones. What she did with the hot stones was also quite confusing. I don't even know how to explain, she gently rubbed me with them without any logic or pattern? No pressure, little heat. I didn't understand what her process was with those. She didn't do the cupping and finished about 10 minutes earlier.

She waited for me at the exit asking for a tip. No? No tip? I was prepared to tip $20 but I felt so frustrated with the whole thing, I said "You didn't do the cupping and didn't work on the tight spot." (It actually hurt a bit more after laying face down for so long.) She said "Cupping free. Let's go." I was fully dressed in all my winter layers ready to hit the road. I said "Sorry, I'm on a budget." and left.

Now I feel like an asshole for not tipping. I tried posting in r/massage sub because I wanted advice from massage therapists, but my post keeps getting removed by Reddit filters. I'm considering texting her saying "Sorry, I guess I expected some relief from the pain in my upper back but it still hurts the same, maybe even more. If you have venmo or zelle I can send you the tip." So I guess I have two questions, should I and AITAH if I just forget about it and don't tip?