Your plant has been visited by a pest that has eaten the leaves.  This could be a variety of pests like aphids or slugs.  There also appears to be a plant nutrition issue Perhaps related to or caused by the pest damage.  Unsure of your planting method, waterRing schedule and sun light hours, and placement near other plants In your garden.  If possible could you replant in a larger or different pot Using fresh potting soil (organic?) and give it a new start? You should do this if possible with minimum disturbance.  It is worth a try.

Hi Jack - the pests came early on when the plant was younger and in the ground, so I moved it into a pot where I could keep it on a patio. The bugs didn't follow. I left that leaf on because it didn't seem to be problematic. So no pests right now that I can tell. Instead, just leaves being wimpy and curly and yellowing. I've read a lot about how it might be too much water (I was keeping the soil moist), so that's why I backed off and got out the Miracle Gro. I'll try replanting into new soil. Thanks.

It’s good to hear back that you did change the growing environment once already: Nice Job!  Hopefully a newer environment: fresh potting medium and nutrients will help out. You have really tried the logical moves.  The new leaves look promising so far.  There is a possibility that the problem is plant based ie the root stock.  Best of Luck!