A video would have been better

It's perhaps a little difficult to tell what the wave is doing because the whitewater blocks the lower part of the wave. But in the second from the bottom you are leaning forward which is typical of a turn to get speed. Could not tell at all that you were off balance. Hitting the lip would be an option too. That would give the wave more time to form ahead so you can decide what to do. One other thing to consider is taking off deeper. It looks like you missed some more rideable part and possibly could have gotten tubed there too. You are concerned because the lip hit you? It's possible that you are too high up the wave but then again it doesn't look like the wave is breaking completely top to bottom so maybe you are stuck with trying to get tubed in the top part of the wave. If the wave knocked you off then the next time a couple of things to try are first crouch lower. This you can practice at home by standing in your regular stance then crouch down and adjust yourself into the smallest lowest form you can. This won't allow much for balance but if it's just for a short time you can come out and get up to a higher standing configuration (also you can put your hands on the deck of the board for balance) The other consideration is if you think the lip is going to hit you then turn down the face and lean into the lip. The idea is to try to get your configuration so that when the lip hits you it is pushing you down into the board instead of sideways. This will be a exit through the lip. Of course if you can go lower on the wave that might help too.