need some overall advice (fit / cut / colour of shirts) very lost!

I basically have two styles that I'm wearing.... a shirt over a t shirt, or just a shirt. I wear usually white trousers or beige chinos as you can see in the pictures, but I also own some olive and black chinos too. I am usually NOT that bearded like in the first pic, I mostly am clean shaven or just a few days of letting it grow or so. I want to hear your advice from all perspectives, but my main doubts are: With the open shirt, that's a different cut of shirt link, but I'm not really sure its the most flattering. The collar seems large and idk if the whole camp collar thing makes sense. Like would I not literally just be better taking a normal button up shirt like from the second pic and just opening that over a t shirt instead? The t shirts I own are black, a darker grey, and navy. Maybe it would look better if I got some brighter stuff for summer? But I'm pretty pale so surely that just doesn't work. The fit of the shirt in the last pic. It feels a bit tight across the chest and I don't like how the bottom of the shirt splits like that. Supposedly 'rounded hem' shirts just fit this way but I know nothing. It's an XS which feels absurd (172 cm / 67 kg) but the length is correct no? So any bigger and it's just far too long.