Difficult to find the perfect size clothes

Difficult to find the perfect clothes size sweatshirt

In this sense, I wanted to ask if you have any suggestions and help you can give me regarding the size of clothes in sweatshirts and t-shirts. I am 1.70 m (5'7) and weigh 63 kg (139 Ibs) and I have difficulty identifying my clothing size whether it is S or M, although 90% of my clothes are M, sometimes I feel that the height of the front is a little above me, but I have 2/3 M pieces that fit me perfectly and in the right proportions. When I wear S I feel tight in the chest and in the width of the shirt on the back of the sides, so does anyone have any suggestions on how to get out of this indecision in terms of clothes because I feel that M can be big but sometimes S It's also very short knowing that I'm not exactly skinny. Thanks everyone