^^^^ what they both said! All else being right (i.e. reach to the bars), and allowing for photo distortion, your photos indicate the bike fits you very well: that seatpost extension is more or less what one would expect. If you are 5'9, and your leg extension is right, then you likely (like me) have longish legs/shortish torso for your height. At 5'8.5", and with a true 33" cycling inseam, I would have a 'look' on a Medium Crosstrail almost exactly like yours. For me, at least, a Large would be huge, and way too long in reach to the bars.

If you don't feel cramped or too stretched out, the size is very likely precisely right for you, and you can make a minor adjustment to that with stem length (don't make that adjustment by sliding your saddle forward/back).

Finally, and opinions do differ on this, I am of the "if borderline between two sizes go with the smaller". My reasons are as yours, plus the fact that one can, within reason, make a very slightly small frame fit 'bigger' (stem; seatpost), whereas it is quite difficult to make a slightly too large frame fit 'smaller'.