Here's the link to the walkthru thread, it's a very good resource, http://forum.ea.com/eaforum/posts/list/9043283.page
I would think from the fact you seem behind the building curve you must be house farming. If you are and you are getting lots of XP you'll be levelling up quicker than the game expects you to be doing, therefore whilst you may be on level 17 you might be many levels behind with buildings.
Just be patient and you'll eventually catch up. It took me to reach and be on level 23 for many weeks before I eventually caught up on the game where I am doing a bit of farming.
Good luck and keep tapping!
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