Its all in mind. You do masturbation to get pleasure , just enjoy. Stop worrying. When u have sex then will worry if u have issue of premature ejaculation. If u masturbate u cant have night fall. Thats science.
Next Steps
Spending too much time on penis, masturbation and sex. Occupy ur mind with other things also. Watch series, do yoga, listen to music.
Health Tips
if u still feel anxious take a consultation.