Based on our posts, it sounds like you are stressed and anxious. Those can cause the symptoms you are describing without endometriosis involved. It can be part of IBS which is very much affected by stress and which many women with endometriosis deal with, and your symptoms could also be because of having a cyst.
You might want to talk to your doctor about your anxiety issues and ask if you should be making some medications for it until your surgery. That could help with the weight loss issues and painful bowel issues.
You should also be talking to your doctor about the weight loss as you could end up having your surgery cancelled if you are underweight as it could be too risky to proceed. Your doctor may have some suggestions for preventing further weight loss or increasing your weight. If the issue is IBS and stress, there are medications that can prevent your system from letting everything go through so quickly.
Worrying about if things are really bad or not is not going to change the big picture. And based on what you have shared in your various posts, even considering things could be bad aren't going to cause you to find a more skilled surgeon because of your circumstances. Thus, you need to take a deep breath and realize it is not in your control and stressing is only making things worse. Yes I know, much easier said than done. I know first hand how stress can cause weight loss and pain issues. Been there, done that.
in there and get in touch with your surgeon. If your surgeon won't help, talk to your GP.