Is it obligatory for a young man who was addicted to masturbation and is currently suffering from erectile dysfunction, premature ejaculation, and low testosterone, and fears he might wrong his future wife, to inform his fiancée of his health problem or not?

You are obligated to promptly repent to Allah Almighty from the forbidden habit by abandoning it, feeling remorse, and resolving not to return to it. If your repentance is sincere, then do not worry, for "the one who repents from a sin is like one who has no sin," and will not be punished, neither in this world nor in the hereafter. Proceed with marriage and dismiss these intrusive thoughts. If your illness is temporary and can be cured with treatment, then you are not required to inform your fiancée. However, if it leads to the loss of the ability for intercourse or procreation, then you are required to inform her.