Also, when I first added the solution; after the very first drop tiny flecks of grey appeared. When I shook the tube to mix it as informed, the urine turned cloudy. This kept happening until I reached 24 drops and then it was a solid grey not just specks of grey.

That many drops, despite the odd colour, signifies high sodium excretion, hypo function adrenals according to the Osumex standard ranges on that test.

I can't find any info on silver nitrate or potassium chromate used in the titration test turning urine grey, and why. It's quite intriguing. Maybe ask a chemistry nerd on a forum :-)

Thyroid test results are often told 'normal' when you can be high or low within the range - 'Stop the Thyroid Madness' website is worth reading through - loads of good info on adrenals and tyroid function, symptoms and test result interpretation and which tests to get. Your doctor probably just tested TSH...which doesn't really give a full picture of thyroid function.

A hormone panel - sex hormones, full thryoid panel, adrenal hormones - blood and saliva would be the best route.
Canaryclub.org do the cheapest 'pay yourself, do at home' blood spot, and saliva testing i could find online. They do a good 'comprehensive' panel including all the tests i mentioned above.

You could easily spend hundreds on supplements right now to treat your symptoms, and it's a hit and miss journey that takes many months/years. Getting some diagnostics, coupled with symptoms helps give a clearer picture of what's going on and how best to treat.

Also you could consider NB which tests hair for mineral inbalances, metal toxicity - gives indication of adrenal and thyroid balance too, aswell as a whole host of other health info.
There's a 'Nutritional Balancing for AF' forum on here which has loads of info on that healing route.
It's a long-term route to balancing minerals in the body and not a quick fix scenario, it requires dedication to reap benefits. Those who have followed it as recommended by a *good* practitioner have been making progress and there are some who are almost recovered doing that route.
Some have been on the program for years and still not doing well but IMO it seems that there are practitioners out there who really don't have the expertise to deal with complex health problems. I chose a crappy practitioner. Also like i said, it takes commitment and dedication to follow the program, some don't have the will, time or funds and so don't fully benefit.
Ask on the NB for AF forum for a good practitioner in your area if you're interested in this.

I personally went the NB route initially, and still incorporate the program loosely into my protocol.
The hair test revealed certain hormonal imbalances so i then went the hormonal specific testing route to get more definite info on levels...which allowed me to refine my protocol and got me from being bed-bound to being more active.

Good luck on your healing journey :-)