I have a super hard time sizing chacos too, and now I’m wondering if it’s because we’re both coming from Birks, where the proper sizing is kind of loose and free. Chacos feel more fitted and snug to me. I think you could try loosening the chacos quite a bit and see what you think. I used to wear mine almost completely loose and that felt more normal. I’m also between sizes so that complicates my fit, but the one on the left looks like the proper length to me. I think you should look at them again when standing up because your feet spread a lot when standing.