I'm sorry you've had such horrible experiences w/ LP. I would recommend requesting LP by fluroscopy, if possible. The radiologist can see where the needle is going and make adjustments as needed. It's still a needle in your spine, but reduces the number of attempts and mistakes. I guess I'm lucky because my neuro-ophthalmologist and diagnostician felt that LP was barbaric and should only be used for diagnosis and emergency purposes..I've only had a dozen or so over the past 15 years, but still have damage to my sciatic nerve.
Personally, I would much rather have a shunt surgery every few years than a LP every few weeks/months. Every time you have a spinal tap it creates damage and scar tissue. With all of your experiences I would be more concerned about permanent damage from LP than a shunt surgery. I know it's a scary process, but I would do the research and talk to your neurologist about the options..maybe consult with a neurosurgeon before you rule it out.
I hope you find some relief soon!
Julie