Of course you're gonna end up too fat, i'm 100% sure you're not tracking what you eat using a kitchen scale and myfitnesspal. You have to be in a moderate caloric surplus and hit your macros properly.
you're not losing muscle, your fat gives you the illusion that you have more muscle than you think you do. so when you cut down and lose fat, you're seeing how much muscle you really have... which is not a lot. Look at some real natties that cut down for bodybuilding shows, they look horrible because it's honestly hard to build a lot of muscle naturally. but basically what @matlockmatt said is the correct answer.
Depends on how long you've been lifting. Less than 1-2 years, you're just eating too much, scale it back a bit. About 300 calories. If you're mid-intermediate or higher, bulking is a scam, it'll just make you fat as a natural. You could also have low T3/T4 and/or low testosterone.
Sounds like you're a good candidate for the legion of needle samurai. Nobody gets impressively strong or big without magic muscle elixirs or top 10-20% genetics, and it sounds to me like you're missing the latter.
What you perceive as "size" is very likely intramuscular fat, water, and glycogen. Naturals who get lean have their muscles flatten out as a consequence. And because mass moves mass, the simple act of increasing your body weight will make you stronger even if a negligible amount of that weight is contractile muscle tissue. It sounds to me like you've hit your genetic ceiling for muscle growth and are mistaking other forms of mass gain for muscle gain. It's a common mistake.
