I hve low testerone level n small and soft penis i m so worry i m 18 yrs old?

Age of puberty: varies with each individual, although for most boys starts at 12 years and by 16 should be nearly complete. Some start much later, and that may be your situation, in which case you need to be patient. The progression is first the testes enlarge, produce testosterone, which causes increase in sexual hair and penile growth. Chromosome tests can be done to check for genetic cause like XXY.