I don't really know what to do. I have had sex once with a fat and ugly girl and neither I nor the girl enjoyed it. My dick is like 5.5" length but only 4" girth, which is thin like a finger. For reference how small it is, I have to buy extra small condoms because regular ones are too big.
When I look at porn with hung dudes it seems that it's much more enjoyable for both parties. Like if you have big girth you stretch the girl out, she moans a lot, enjoys the pressure, fullness, the visuals when giving a blowjob etc. A small dick is just so unappealing, has zero eroticism, it cannot make a girl horny or rather turn her off completely.
Should I even try to pursue girls or just live my life alone? Even if I managed to get a girlfriend she would not be attracted to me sexually and she would only have pity sex 1x a month probably.

The bigger your body, especially your hips and thighs get, the smaller it looks. Mine is like 5" long and 4" girth. I have to buy extra small condoms because regular ones are baggy.
I have never had a girlfriend, obviously, and know I am debating if I should even lift. With the small unlikely chance that a girl sees me naked she will laugh and brutally reject me.