1 year old has hit all the motor milestones

My one year old son has hit all the milestones including walking, except for one potentially most important one. He doesn’t get himself into standing position on his own. He always needs to be holding onto something to stand up, but then will let go and stand independently and start walking. When do babies learn the skill of pushing themselves up from sitting to standing all by themselves?

Another side note, I feel like he’s not really saying words other than mama and dada (much less connecting that that’s who we are) and it doesn’t seem he understands much of what me or my husband are saying most of the time. He babbles all the time and we talk to him every chance we get. When should this change and should I be worried?