As per multiple scientific research, Regarding length of penis while erection, most of the males are much concerned to have more lengthy penis to satisfy female. But let you know scientific fact that Vagina's only inner 3 inch part is sensitive, inner to it is not sensitive. So in erect position, 4 inch length is sufficient to give enough satisfaction to female.
Next Steps
In ours culture, some misnomers had been spread much like more penile length-diameter, higher sexual intercourse timings are mandatory to satisfy female partner.
Health Tips
In yours case, penile length is fine. No need to worry. Happy to help online. You can consult me in case of need. Take care!!