Homebrew Path of the Totem Warrior for Grapplers

After spending lots of time reading up on Grappling in 5e, the Grapple Manual 2.0, and all kinds of posts and what not… I felt kind of let down. It’s neat and all, but I simply felt like something was missing. I sat down and wrote up a new Path of the Totem Warrior for Barbarians and would love some feedback, please don’t be to harsh.

Totem Spirit Serpent

Entangle

At 3rd level while raging you count as one size category larger when you grapple. At 7th level you count as two size categories larger when you grapple. At 11th level you count as three size categories larger when you grapple. At 17 level you count as four size categories larger when you grapple.

Constricting Squeeze

At 6th level as a bonus action you can begin to crush a successfully grappled opponent. Make another grapple check and on success you cause 1d6+str damage (failing the grapple check made to cause damage does not break the grapple, but causes no damage that round). Each consecutive round that a successful grapple is maintained with damage, the crushing damage multiplies. First round 1d6+str, second round 2d6+2x str, third round 3d6+3x str, and so on. This damage climb resets if you move, or if the target breaks the grapple, or if you fail the grapple check to cause damage that round. If raging, the bonus damage from rage is included and would also multiply.

Spirit Walker

(Same as RAW) At 10th level, you can cast the commune with nature spell, but only as a ritual. When you do so, a spiritual version of one of the animals you chose for Totem Spirit or Aspect of the Beast appears to you to convey the information you seek.

Serpents Strike

At 14th level while raging if an enemy enters an area within your movement speed and you can still move, you get an AOO to pounce and initiate a grapple. If the grapple is successful your target is grappled and also pinned (both you and the target are restrained until the grapple ends).

What do you folks think about this for those looking to have some grapple options, is this a balanced option to the game mechanics?