Not eating enough, but not hungry

cedarghost

I really struggle with this. I am 42, 6'5'' and currently weigh 224 pounds. I have been working out for about 6 weeks. I started at 236 pounds.
3 days a week I do a 15 minute high-intensity total body workout, circuit style to maximize EPOC. Then one day a week I do 15 minutes of HIIT using cardio equipment.
I am getting stronger and have lost a couple inches in my waist, but worry about not eating enough and losing lean mass. I have played with calorie goals of anywhere from 1400 to 2000 per day, and I really struggle to hit 2000 a day, though according to the tools on this site, I should be eating even more on my workout days. I try to fill in the calories with nuts, fruit, etc. I quit drinking soda and only drink water and milk when I have a protein shake, but I feel like I am cramming it in to hit 2000 calories.
I quit eating breakfast, instead opting to fast for 16 to 18 hours and eat for 6 to 8 hours. Started this about a week ago, but haven't really seen a benefit yet.
I guess I just have a problem believing that I need to eat more, when my body is recovering well, I am starting to see muscular definition I haven't seen in years. And I am doing it at less calories than what is recommended according to my BMI, etc.