Weightloss. I see progress and then I quit.

I’m 52yo and 50# overweight. I joined in June to lose 8#. I lost 5! That wasn’t enough. I felt so disappointed. My thought was I’m so overweight that I should drop faster and then I gave up. I stopped doing all the things that I thought were sustainable. I was eating on protocol (noon and 6pm. 4oz of protein and veggies). My caloric intake was around 700-800 calories. I was not intentionally counting calories (that is the ONE weightloss program I never participated in) but I was curious and then surprised others were eating 1200+ calories and losing weight. Plus, how do other scholars get that many calories in just two meals a day. Can you help me with that? Should I increase the amount of food I eat? I have got to lose this weight once and for all but finding it hard to get back on protocol. Thanks.