You did not have "prediabetes" but insulin resistance (high insulin to keep the blood glucose normal) probably from bad diet with too much simple sugars - your fasting blood glucose of 96 was not high enough and your A1C was high normal at the boundary with prediabetes. Your A1C is slightly lower now, mostly because you changed your diet and lost some weight. You don't need any Metformin or other drugs for that.
The elevated CRP and joint aches can be caused by gazillion of problems - arthritis is a symptom not a diagnose of the root cause. Your immune system is attacking your joints and there may be a reason for that - it's frequently triggered after a bacterial or viral infection. If you think it is a bacterial infection, the most probable location is the intestines and the oral cavity - they constantly exchange bacterial flora. A reasonable approach is to try probiotics that have anti-inflammatory properties i.e. will calm down your immune system. Important foods to avoid are inflammatory simple sugars glucose, sucrose, fructose(even in fruits and especially junk food) and lactose in milk - they feed auto-immunity. If you suspect gluten as a source of inflammation, then test for that. The hydroxychloroquine is covering up the problem, not addressing it.
Low SHBG can be either genetic or due to diet high in simple sugars (elevated Triglycerides is an indicator of that):
Sex hormone-binding globulin (SHBG) is a protein produced in the liver. It binds certain hormones. When SHBG is low, more of these hormones are available, and when it's high, less are available. Here's what this means, warning symptoms, management tips, and more.
www.healthline.com
Your free T is completely normal at such a low SHBG so it is unlikely that TRT will solve any of your problems. Claims that "low T is associated with this and that" means absolutely nothing in medicine - take older people, they have lower T and you will find all kinds of correlations with other deceases.
So my advice is better diet, probiotics, and find the root cause of the inflammation, which probably means finding a better doctor. Don't try to explain everything with high/low T or E, as they often do on this forum - it will lead to years of chasing your tail.