My first comment is that your seat looks high. In the first photo, your knee bend is about as straight as I'd ever like to see and you have your foot pointed down. Maybe OK if toes down is how you ride all the time. I mention this because your ideal stem will always be dependent on your seat position. (The seat height guide I and others use is to sit on the bike on a trainer or leaning against a wall and rotate one pedal all the way down. Now I place my barefoot heel on the pedal spindle. Perfect seat height is when I can either straighten my leg or bend my knee a little and not rock my hips at all as I do it. (Some like a slightly higher seat and do the same test with heel-less cycling shoes or slippers. Once you've found what footwear works, keep it!
You may find leaning forward and reaching further easier with a lower seat and more knee bend. This will have rewards both in comfort and your legs will thank you for being more aero on that long upwind day,
Select a stem that feels right with all or perhaps all but one spacer under the stem. Because, if you ride enough, you'll get more comfortable and want more reach. Well, removing 1 cm of spacers is almost exactly the reach addition of 2 cm more (horizontal -17 degree) stem. (Neat little college budget trick as well as the way to make a whole bunch of stems work in a pinch.)
Another point: Your elbows. From these photos it is hard to tell how much you have them bent. More is always better! (Within reason.) Too straight and bad things happen when you hit the pothole you didn't see. (Yes, little excuse for not seeing it riding solo but in races, in pacelines, in dense traffic, that pothole might be only 3' away before it's even in sight. Riding solo? Daydreaming is one of the perks!)
Shortly after college, I joined the racing club of Boston. The racers there with a lot of experience quickly told me to lower my seat! Then in rides, stressed elbows bent and rotated out so all contact with other riders happened on those non-rigid arms and kept my handlebars free from hooking other rider's hands, bars or legs.