It doesn’t look too big to me, you already look better than most MTB nodders do on road bikes,
50mm?!? It’s a road bike, put a 100-130 on it and it will handle properly, ride some more and get more flexible, you actually look like you are in the tops position as you are quite upright but are on the hoods.
As for the neck pain, I have been off the bike for 6 months and expect a bit of neck and shoulder pain until I get back into it, your core will get stronger and start to support you not your arms shoulders.
Ignore the anecdotal “I’m x ft and ride an xxcm” sizing advice as it’s meaningless. People have different leg/torso/lengths/proportions and bikes are sized differently, plus head tube heights/stem spacers/stems alter cockpit length.