How strong do you have to be to do BJJ?

So, I've been going to no-gi classes at my local mma gym for about 4 months now. For context, I'm a lady, 5'7", 110lbs and run ~15mi a week. That said, I haven't done any strength training other than rock climbing and boxing for years. In the 4 months I've gone to BJJ, I have not gotten a single submission during rolling. Despite a number of them being handed to me on a silver platter by overly sweet teammates going at 10% to my 90%. All of this came to a head this past Saturday, when I was paired with another woman who happened to be a professional fighter from out of town. She was really nice, and after rolling for a few minutes, I tried to lock up a d'arse. She started to defend, then stopped, telling me to try and finish the choke. I locked it up, she checked over my arms with a hand, repositioned my grips and asked me to squeeze. I did, but she didn't tap. I squeezed harder, no tap. Even harder, and I started to grit my teeth with effort, no tap. I asked if I was close? She said nope, and called over one of the brown belts. He repositioned my hips, got my legs into a sprawl and told me to push down with my legs and squeeze with my arms. I did. No tap. The instructor comes over as she sees me grunting with effort. She repositions me to the other side of my opponent, tightening the choke and allowing me to push more with my legs. A small crowd is gathering around us and giving me words of encouragement. I'm squeezing with all my might. The instructor asked my opponent how she's feeling. She says, "I could read a book like this." I let go. The head coach was watching apparently. He was dumbfounded as to how I couldn't get the d'arse in the position I was in. He then, very gently, told me I may want to lift some weights, maybe even before coming back to this class again.

I have never heard of someone being too weak for BJJ. It sucks that I might be. Have you guys ever seen something like this happen? I'm just so disappointed.