
Without an adequate resting period after a workout, the fact is, you won't see any real gains in muscle mass other than the temporarily increased size from inflammation (study). That's probably the main reason why you're trying "so hard" but can't see the muscles growing, aside from not having a correct diet and/or supplementation, or having a really small number of muscle fibers due to genetic factors, or a disease, or a syndrome (or the combination of these), which eventually brings you to the conclusion that you are a hard gainer, although that's probably not the case.