suddenly hard to put to sleep..yikes

So DS is a crappy sleeper who nurses all night long. What has been my saviour though is that he's been easy to 'put to sleep'. 5-10 mins of nursing and he'd be gone for a few hours at least.
Recently it's taking forever and is frustrating me. He's almost 20 months and learnt many new words recently which he wants to practice .
He almost falls asleep and then jumps up and spots something in our room (we co-sleep) and names it e.g 'book, book! Mummy, book!' or tries to get off the bed and leaving the room shouting 'Go!'. It goes on like this for a hour or so. By which time my evening is almost over.
He's popping on and off my boob all the time and doing lots of nipple twiddling and kicking which also drives me mad.
I'm a bit concerned about safety too. He's getting up and hanging/leaning over the bed rail. We've always put him to sleep and left him in our bed while we have grown-up time.
I'm starting to question our AP beliefs. I resent the lack of sleep and feel so touched out. DH is a big help. He always responds to DS if he wakes up before I'm in bed but he's sleeping in the guest room due to DS waking and tossing around so much. I miss him.
urgh. Is this a phase that'll pass Mamas??