First, congratulations on your body transformation. You are clearly working very hard toward your goals and have made tremendous progress since January. Your gynecomastia seems very mild, though a physical exam in person would be more relevant than pictures. Regarding your abdomen, you clearly have been able to attain a six pack, which means that your body fat composition is very low (likely well under 10%). The excess skin that you pinch is exactly that, excess skin. No amount of diet or exercise is going to tighten loose skin. That being said, if you were to come to see me, I would very much discourage a tummy tuck, which is really the only guaranteed way to remove the excess skin. Everyone has loose skin, which is why nearly anyone could have a tummy tuck. However, that doesn't mean everyone should--scars are not always a good trade-off and for you, I would not recommend it. Again congratulations and best of luck!