Ah man, I hate that too...2015 Macbook = sealed unit, no upgrading. It sucks,
I've been on and off looking at maybe getting a surface pro and I'm more interested in ram than I am overall cpu performance (that's what my desktop is for) but ram is soldered so forced into buying more expensive version (that's putting me off) just for more ram...
Oh how I miss the gold old days of being able to upgrade things like ram, I hate it being soldered onto the motherboard, same goes for the storage in some cases now too...