Can not penetrate into virgin wife.

Hi, I am married from past 1 year.I tried having sex with my Virgin wife on first night but couldn't penetrate as my erection didn't happen. I tried many times afterwards but couldn't penetrate, may be due to no erection or hard vagina.later I figured out that I had phimosis(as my foreskin never stretches back on erection) , so I did circumcision 2 month back to remove my foreskin,but in this whole 1 year process after continuous disappointment, I lost my sexual desire towards my wife. After circumcision we tried again but still same problem as I can keep my erection hard enough to penetrate and I get aroused only by porn for few minutes. I am struggling to put my penis into my wife's vagina, what am I doing wrong? How can i penetrate my penis smoothly into her tight vagina? Still we both are yet to ejaculate. I am overweight but that should not be problem as many fat man does sex smoothly and had babies. Please help us.