What Causes Low Sperm Count?

Hi Doc
i notice that my wife was not getting pregnant therefore i seeked medical attention and some tests were done which include testerone test and sperm count. i was told my testerone levels were very low and hence my sperm count was also very low. i was put on Steron testerone injections which didn't do much, then i was gaven a NEBIDO injections which after going back for the test my testerone levels increased. However, the sperm count did not increase.
i saw a doctor who introduced me to Himplasha from Himalaya products, i took the dosage i was told but still no results. am now taking Confido from Himalaya Products which i have not finished the course. my question is what could the problem with my low count? the doctor order for the scan of my testis and the results were o.k and in fact i was told my testis were in good shape and normal size, my vains are also good? what other products that you can recommend for my situation?