I know you said that no doctor can convince you otherwise, but your testosterone level is at the high side of the normal range and is therefore proof that one testicle is as good as one - at least from the point of view of testosterone production.
If you take supplementary synthetic testosterone it will simply shut off your body's own natural production and you will end up back where you started withion a few weeks
Transplantation of testes (or pieces of testes) was certainly popular for the first half of the 20th century - it was particularly popular with the doctors who made fortunes out of it. It was abandoned because advancing medical science showed that, without antirejection drugs, the testicular tissue was simply broken down by the body so after a few weeks the testosterone levels fell right back again. Turns out it was simply a placebo treatment that exploited vulnerable men. In case you're wondering, they didn't transplant whole testes into the scrotum, they inserted them (or mashed up extracts) into the abdominal cavity, so that no-one knew whether they were working or not. If they had been put in the scrotum it would have been obvious within a few weeks that they were breaking down and being absorbed by the body.
It seems to me from what you say, that your problems stem from the loss of the testicle, not from loss of testosterone. No type of drug (or transplant) therapy is going to help you get over that trauma - it needs to be addressed in the same way that women who lose a breast are treated - by support, counselling and psychological therapies. I know you won't like this, but you are not going to make the trauma go away with extra testosterone, however you get it into your body.