You are more active than you were, so you must be converting fat to muscle and - even more importantly at this stage! - supportive/connective tissue, and doing cardiovascular improvement.
I fully understand the frustration; I never lost more than 4kg from starting weight 4.5 years ago and in fact weigh more now, no.matter the combination of diet, booze, exercise and illness, I never looked any slimmer or trimmer (and again, look fatter now) but the results absolutely speak for themselves, I move more weight more times and hold better form doing it.
That is intended to say - don't be disheartened, mirrors and scales only tell a specific measure of the truth, not the whole truth.