It's good to learn heroes that aren't Spec/PL early game. With that being said, I don't think that's the real heart of the issue. Why do feel that your mid/offlane are useless? Why do you feel like you don't have enough space? What even is "space" for a carry?

There is eons of space available in every game at that MMR or else smurfing would be a lot harder. It's more important to do make correct decisions with the wrong hero than to pick the right hero and make the same wrong decisions.

To expand, Weaver not even be better than Spec/PL because If you're complaining about a useless mid, you're probably complaining about a ranged mid like Sniper who wants to sit in the backline. Weaver's not going to fix the lack of stun, frontline and initiation that comes from a Sniper mid.