Hey congrats on putting in the first 6mo & thank you for your service!
How often do you want to be in the gym? What exercises are you doing now & do you like them? Do you have injuries that limit your exercise choices? Do you have time/ability to recover between workouts (eating sleeping, stress free down time, etc)?
Best program is one that you enjoy & can recover from & make gains & not hurt yourself, imo. What have you been doing for the first 6mo? Personally I did a push pull legs 5-6days per week the first 2mo & been doing something like 5/3/1 4days/wk since then. Can't do leg extensions or some heavy shoulder workouts due to my injuries. Can do squats & most dumbbell movements tho. It seems to me that progression of work performed over time is a very important part of any "program". Are you lifting more weight in your workout today than in a similar workout last month? Did you either lift heavier weight or perform more reps with a given weight? Progression.
What to eat?
Whatever you can get away with given your goals & tastes lol. My fitness pal is an app that can help you calculate how many calories your body needs & provides a caloric total if you accurately log your food. Of course the "rules" say less processed food & less sugar & alcohol are good guidelines. I'm a 6'1" skinny guy & I'm eating ~3000cal daily, more on lifting days less on off days, trying to slowly bulk.
When to J/O?
Bro it's the over 35 forum. Every chance you get lol.
You look muscular up top for sure but as mentioned, your legs are a little behind. @gorillavanilla recco'd the super squats book to me (blessed with small girlish legs lol) & I literally grew into then out of my jeans over ~5-6wks.