Great job Joanne. I loved Regan’s coaching journey with you and I also actually can see that already, you have some of the answers hidden in your own reply.
Images – if you changed your MAIN image, that would be one of the direct reasons that your sessions would increase. If you changed your secondary images but didn’t see a drop or increase, keep these new ones and, by your own omission “my bullet points are a bit longer than the bullets from my competitors. I would say – my bullets are more keyword-stuffed.” – sharper and shorten up your bullets and leave for 7 days to see a change in conversion. Long bullets do definitely put people off and if they are too long the customer may only get to the first 2 bullets so you can effectively promote ALL your benefits to them.
You said that you were “pretty happy with 20 sales a day” which is great, so for a cost-effective way to get a tiny bit more at no cost, is to shorten those bullets so all of them get read.
If you were more concerned about 20 units per day, there are options to do a mini boost of sales (through a launch service) but this costs money and you need to balance what you want to achieve and what you are prepared to invest to do this.
I didn’t want to jump in over Regan, but I loved the commentary between you both.