Sounds about right seen as the 1st dragon your supposed to fight is near white run which where you learn your dragonborn ect an the preferred dawnguard quest rumour start is level 10, so jus fast forwarding straight to dawnguard before anything else is dragonless makes sense.
Maybe you should of done that beginning dragon 1st do get the dragons flowing, I didn't think the attacks started on towns till you started dawnguard so you would of been fine