Oh the frustration I know!! My 10mo son took a while getting to sleep as well. He went through a time where during the day i would spend it either feeding him or fighting to go to sleep...not a fun situation. My doctor told me that the little ones will change their sleeping habits and during which will go through bouts of not sleeping. Doesn't help I know! But, the best thing you can do is try to establish that routine (like you are). The problem with rocking is that you may be getting him to sleep, but he may become dependent on rocking in order to get to sleep. You may try putting him in his crib while he's awake and happy, instead of just being a sleep area. My husband and I always try to read some books in his room too before we put him to sleep. And when he went through the stage of fighting it, the first night i gave him 10 mins crying, then went in and calmed him down, then 15 mins crying then when in and calmed him down, and so on, adding 5 mins each time, and each night started 5 mins later. Eventually you will work through it. The thing you want to make sure is you're not setting yourself up for more sleeping struggles, but giving into the crying...it killed me but so worth it. Now, we place my son in bed awake and he falls right to sleep.
I would also call my dr, and just make sure he doesn't think something else might be up that you're not aware of. You never know!
Oh one question, when does he typically nap during the day? You may have to adjust that to get the nighttime better.
Sorry I can't help more.