It’s funny that I just joined thunders after being prevented from registering for the last several months and then one of the first threads I come across is yours.
You have almost the exact same measurements as I am naturally and I have never had a problem satisfying a woman. I am also in my early 20s, so I know how you feel. I went through the same thing, but it isn’t worth pining over. Your equipment is perfectly capable.
My current measurements are 6.375 bpel x 4.75 mseg, but even with my natural 4.5 mseg, my girlfriend of 3 years on and off has always cum before me - usually multiple times. I must say though, I think that for women, a good portion of the pleasure comes from their feeling of a passionate connection with you. Also, after being with my girl for this long, I’ve noticed that if she doesn’t move/work with me a little bit, it’s much harder to make it happen for her.
Tl;dr - you’re perfectly normal and capable, so don’t sweat it