I lost a testicle due to torsion... Am I in fertile or also have low testosterone... Two urologist say it's nothing to worry about?

Monitoring advised. The majority of young men losing a testis to torsion suffer no significant problems of fertility or testosterone levels. Like any medical condition however, there is a wide spectrum of results different patients may experience. If concerned, you may monitor your levels and measure blood tests in the future to check your status as indicated.