My question is do you guys recommend me sticking to learning UE4 for 2D Mobile Games? im learning UE4 For 3D Games already which its great for . but i also want to develop 2d Mobile Games. but i hear that the UE4 is too heavy & powerful for 2D Games , i keep hearing that , i kept reading about Tappy Chicken and they kept emphasizing on the size . should i just use Crappy Unity for 2D Mobile games? or should i invest time in UE4 for 2D Games ? im already learning UE4 for 3D so it will ideal to remain in the same app but i dont want to be limited or use a system that is only good for 3D and only doing 2d for political purposes…please as detailed as possible. appreciate it!
for mobile 2d i’d say unity has the advantage atm, hopefully not for long though!
In my opinion, since you asked, I would suggest that you experiment with Building UE4 from source while taking care and research into what you can give and take to make the engine lighter.
I personally would stick with the UE4, because they are constantly improving the mobile game features + you already know how to use the engine 
Regarding to the package size -> you can find some workarounds/ideas on the internet:
https://forums.unrealengine/showthread.php?74015-Mobile-Game-Package-Size-is-so-huge
https://docs.unrealengine/latest/INT/Search/index.html?q=mobile+game+size&x=0&y=0