20 years old with Chronic Back Pain

My back pain started when I was 14 and I always assumed it was connected to my backpack. I walked a mile to and from school everyday with a 25 pound backpack full of textbooks. The pain has continued to progress over the years and I am at a loss for what it might be. No doctor has taken me seriously, and I can only assume it's because of my age.

I feel the most pain on the right side of my mid/upper back right along my spine (T4-T9, the most pain being around T6) I almost always feel a dull ache that will turn to stinging and numbness. It gets so inflamed that I can feel a ridge along my back. Extreme pressure brings very temporary relief, as well as heat and menthol. I'd rate the worst pain I feel a 7.5/10.

I was convinced it was nerve pain because of the numbness, but my chiropractor told me that since the pain doesn't radiate, it is not nerve pain. I was told it was a rib shifting out of place, but after many chiropractic adjustments and no relief, I don't think that's the case. I've been cleared of scoliosis and posture issues being the cause, but have never had any kind of scans. I'm nervous to go back to a doctor in fear of not being taken seriously.

My dad had arthritis in his back and shoulder and he always seemed to be in constant pain like I'm experiencing. I never imagined it may be arthritis because who gets it at 14 years old?? I'm just feeling very hopeless, as this is affecting the quality of my life at 20 years old. If anyone has any similar experience or ideas of what this may be, it would be very much appreciated