Struggling with Chronic Pain and Dismissal from Doctors

In 2017 December I went to an event that seemed to trigger the following January acute symptoms of intense back pain, spasms, and what would become an increasing loss of being able to bend forward or twist, and eventually to include hip and pelvis plus neck stiffness and the inability to turn my neck much. I went to urgent care and they gave me an x ray. the lady on the phone said it was 'degenerative joint disease.' I didn't have a provider at the time, but established one quickly. she dismissed the claims, saying it was just bone spurs and "they don't hurt." fast forward through two more providers and I finally got one to take me seriously. she ordered a bone density scan cuz I also lost height. the scan was 'normal' but I found out later they were looking for osteoporosis and NOT osteoarthritis which can show up on scans differently(apparently bone spurs and osteoarthritis can make you look like you have normal or more bone density unless you know what you're looking for). I've gotten physical therapy, medications, and the like but it's becoming increasingly clear I'm slowly becoming more and more disabled and I'm looking for them to officially diagnose me so that I can get better medical assistance. people tell me I'm 'too young' to experience it like this and therefore I feel like that gives them an excuse to dismiss me. I am beyond the point of being able to work, and my own partner has become a caretaker to me. some days I can barely walk and bathing is getting hard. how should I move forward? years of being AFAB and overweight have really discouraged me into pushing for what I need, and have also affected how doctors have treated me (you're depressed, you're overweight etc). My dad was diagnosed in the 80s and got surgery, so it does run in the family. I want them to redo the scan and look for the osteoarthritis if I can. if I can't, what other things can I do with my doctor to get a diagnosis?