When I fitted mine about 2 years ago I found exactly the same issues as you - gap all round and gap at the join. I managed to eliminate most of the join gap with some adjusting. After worrying the problem for a while I decided it wasn't going to fall off, didn't look stupid and wasn't a functional piece anyway so I left it. But the next few months wherever I saw a bike with the same piece on it I checked it out and they were all just like mine - usually worse.