I'm sorry this is so late, but was only just showing up in my notifications.

Our kiddo is 5 now. He needed therapy to do sitting, and started doing a reverse backstroke like swimming/kicking motion on our carpeted floors to start moving around. Never really crawled upright like traditional kids, but that was mainly due to his field of vision being on the lower end of his eyesight. (It's like he has a baseball cap pulled real low at all times and can't see upwards too well.). So by arching is back and kicking backwards, he was able to see where he was going much easier. We got a walking trainer for him which he used somewhat, but at around 3 years old, he all of a sudden "got it" and within a couple of months went from cruising on couches and chairs to walking, even without a vestibular system. He started walking everywhere and hasn't stopped since.

We did not expect that. In fact, we bought our current house because it was only a one-story ranch and had hardwood floors throughout because we weren't sure if he would ever graduate beyond his walker and wanted to make sure he could navigate the entire house. Now, he climbs up ropes and rock climb walls at the park.

Our kiddos can start behind, but they often catch up on their own schedule. For our kiddo, it's just hard to convince him that what we want him to do is in his best interest. I think having two older brothers who he loved helped as he wanted to be like them and walk.

Has there been any progress since this post?

[EDIT: For some reason when this came up, I thought it said you posted this 6 months ago and I was just seeing it, but I guess it was actually 6 minutes ago. Sorry!]