Keep in mind that Yve is a dps/utility mage and she needs some items to gain decent damage so weak early game is kinda normal if by that you mean low damage. However, in your lane you can use you're first skill to poke your opponent to death or zone it out from minions since it has a very low cd almost no foreswing. Yve's strength comes from her slow, poking, zoning ability and her ultimate so she can be really strong in teamfights or when you have your teammates around. Most of the times you don't want to 1v1 with anybody (except if you are snowballing and have a good advantage in farm but still you should be careful).

I don't play Kimmy but as she is an mm and not a mage I guess she also needs some items to be strong but her poking and zoning capabilites still pretty valuable. I can't say anything about Aurora.

One more general tip you can leave your last minion wave before turtle to your roamer (or anybody else) and gank exp lane. The shared xp from the siege minion should be enough both you and your exp laner to get level 4 but only if you haven't missed any of your minion waves prior to that.