Misdiagnosis of FND!

Hello! I'm 17 and new to this site, I've joined because I might have MS... So my first two symptoms of MS were trigeminal neuralgia and leg pain on walking, no matter the distance. I have been to my local GP a number of times, sometimes referred to my nearest hospital. Fast forward to now and I have near enough constant lower back nerve pain, intermittent tingling in my hands and legs, numb patches in my lower limbs, bladder incontinence, constant double vision, trigeminal neuralgia, etc. I was referred to paediatrics in November last year due to my symptoms, and saw my adult neurologist last week. After looking through my notes and seeing my autism diagnosis and the struggles with mental health I have had the past few years, she has given me a diagnosis of FND and discharged me from neurology, dismissing my symptoms as "stress". I have had two MRIs which came back clear, which I'm pleased about but I still think there is another cause for my symptoms other than stress. I thought FND can be mostly caused by stress (but I could be wrong!), and as of recent years my anxiety is still there, but I'm feeling the most calm that I have in years, my family and I took a day trip to go sightseeing recently and I was relaxed and happy, but my symptoms were still there! I was discharged from neurology after my first appointment with no further testing, such as a lumbar puncture, which I have read is another good diagnostic tool as well as an MRI, even if the MRI is clear. I'm thinking of requesting a lumbar puncture? So that's what's been happening lately, and I just feel stuck, and unsure of what to do next. If anyone has been through similar or has an idea of what to do next, please let me know, I'd be very grateful!