They have to learn that they are sheep. That means not petting them any more and not being in the field with them. It seems mean, but by ignoring them you will reinforce that they are different. Can you put them into a field away from you for a bit?
There is lots of discussion on other chat sites about whether or not you should smack them on the nose - it seems not to be a good idea as it seems like fighting to sheep, in which case if you smack them on the nose they will just smack you back. We did once have a very pushy ewe lamb who as she grew got worse and would try to nose dive into the feed bucket in the winter. She eventually got over it when we simply never let her have any food from the bucket, just from the trough. We would turn our backs on her as you would to a naughty puppy and she would just wander off. It was so tempting to go after her to say sorry
She now belongs to friends and is a very happy not pushy sheep.
It is a shame when it has been such fun having them as cuddly lambs, but cuddly lambs do become big, smelly, pushy sheep, unfortunately.