first of all , i feel sorry for you mate. 40 draws and no plat seems rough. Second , sasha is one of the best (if not the best in our curent version) mage in the game. Her skill used in combination with a heavy armor , can make said armor tank a whole lot harder.
That being said , i pretty much subscribe to what sora said : get heavy armors leveled and cc...and fast , since the next star event will require them. That being said, you won't necesarily need 2 heavies cc-ed asap , considering that marribel on the second to last map was used to stop just 1 unit. You can probably replace her , with a high defense duelist + sasha(and get a better healer there , because she IS going to take more damage tho). Since you can get a perfect unit even if you don't get any star on the G map (assuming you 3star the rest) , don't even bother with it. (and that's the one were you really need 2 HAs). Your curent team can't make it
Therefore , i suggest you watch the event guide , and look what you're missing for each map , and try to level that up. If you don't care about the event at all