This sure makes me think that you have a weak pelvic floor causing your bladder problems, and possibly a bladder prolapse if you can feel a lump.

Often the bladder will slip down out of it's normal place and stress incontinence will occur. You can tell you have stress incontinence if you leak urine when you cough or sneeze.

Pelvic floor exercises like the ones Curious mentioned are a good non-surgical way to get this under control.

I'm glad you have an appointment. Good luck; I hope it works out well for you.