49M on Retatrutide, struggling to eat enough calories/protein after 5 years of OMAD. Advice?

49M, 5'9". Did on and off light gym for years. Started OMAD (one meal a day) in 2020 after a ladder fall shattered my elbow, mainly to manage weight. Went from 185 lb to 152 lb by 2023, then hovered 155 to 160 lb. On weekdays I stuck to OMAD, but weekends I'd go big (large breakfast and dinner). Since a vacation last year my weight crept up to 165 to 168 lb with more belly fat.

Started Reta at 0.5mg a couple weeks ago and I'm down to 164 lb. It's been great for killing cravings (sweet tooth, soda, bread, rice all much easier to avoid now, including that after dinner urge for something sweet).

Problem: after 5 years of OMAD I basically have no appetite, even without the Reta suppressing it further. I'm doing 10k steps on weekdays and back in the gym 3 to 4 days a week, but even when I push myself I can't get past 1000 calories a day, and protein lands around 50 to 100g.

Questions:

1-Is under 1000 calories a day dangerous or counterproductive at this weight/activity level, especially while lifting?

2- Any practical tips for getting more calories and protein in when appetite is basically zero? (shakes, specific foods, timing, etc.)

3- Has anyone dealt with this exact combo (longtime OMAD + GLP-1) and found a way to reset appetite a bit?

Appreciate any real experience here, not just "eat more" advice since that's exactly what I'm struggling with.