My daughter is the exact same. We're working with her on helping her trying to walk. She will stand maybe for about 10 seconds when we let go but then she just will fall/sit down.

I'm pretty sure the doctors aren't usually conceded about walking until after 15 months. Will he walk when you hold his hand? Or well he walk around with toys ?

I’d give him another couple of months with walking, my daughter did the same but only because she hated falling on her butt and was determined not to🤦🏻‍♀️ she was walking by 14 monthish. Her pedi wasn’t worried plus given she was a big baby it took her more time. As for the tippy toes I have no clue I haven’t experienced that, I’d being it up with his dr if you have any concerns.