7 month old

My LO just turned 7 months old yesterday. I’m worried that he isn’t where he should be developmentally but maybe I’m wrong. He sits all by himself and he can get into a sitting position from laying down. He is also very very close to crawling the “proper” way. He isn’t pulling himself up onto anything to stand up yet tho. He says dada and baba and makes plenty of noises but isn’t yet saying mama. He also doesn’t really mimic me or his dad. I’m always always talking to him or trying to get him to mimic me and he doesn’t. Should I be concerned?