still mouthing at 15 months??

Hi, Buddy is now into his 2nd year but we are still seeing far too much of the inside of his mouth! its not aggressive, if we smooth him around comes his head and away he starts. He is not destructive but in an idle moment may just happen to chew the corner of a table in passing just cos its there! he is also a very tough chewer of toys, just rips them up, and its inclined to eat anything plastic or rubber, he did used to spit things out but just has to chew. now chew toys dont interest him, is this normal behaviour for his age. I just want to be able to cuddle him a little, even after all this time I had to do isolation last night. (me) advice and pep talk urgently needed please.:confused: