What Causes Penis Size Reduction With Weakness?

hi Doctor Sadie, I am mark from India.I have few question related to men sex health.I am 24 yrs old guy with good health condition.Earlier I use to masturbate once in a day and at that time my penis was strong enough.But from last few months I stopped masturbating because of some personal reasons.I notice that my penis size is reduced & I feel that it becoming weak .I am worried about my future please advise & suggest me . Thanking you Your Truly Mark