I Am Male 61 Years Old And Recent Got My

I am male 61 years old and recent got my wife pregnant and we now have 2 year old baby. But the all sudden I can`t have sex because my penis size is so small and I feel like I can`t satisfy her anymore, I used to have pretty good size penis not it so small I am ashamed. why did this happen to me . my doctor say it ED but it will still get hard but so small. please help me.