Pure Monk Grappler Build

I was thinking about making a pure monk grappler build and I hope that it is possible to do without being too weak for the table.

What I want from the build:

  1. Pure monk build, so no multi-classing (I like challenges in building characters).
  2. The build needs to have good chances for any grappling check (so expertise, good attribute mod and advantage would be great).
  3. Besides multi-classing everything is allowed. The build doesn’t need to be AL-legal.
  4. Well every official release is allowed. No homebrew and no UA.
  5. For attributes, we use point buy.

What I’ve come up with so far:

  • Race: Human

    When you can’t multi-class, you only have the choice between half-elf, half-orc and human to get expertise (with the prodigy feat).

    Because I need 3 different stats, I am actually thinking about taking the basic human, to get +1 in every attribute.

  • Attributes:

    Without race-mod: 13 15 11 9 15 8

    With race-mod: 14 16 12 10 16 9

  • Sub-class: I think the best choices are Open-Hand and Shadow.

    With Shadow I could disable nearly every caster that I want. (Grapple -> Silence).

    With Open-Hand I could use flurry of blows, to knock my grappled enemies prone.

  • ASI’s:

    lvl4: Prodigy

    lvl8: +2 Str

    lvl12:+2 Str

    lvl16:+2 Str

    lvl19:+2 Dex

    If I could get my DM to give me a belt of strength, I could forgo the Str part entirely, but I’m not sure I can convince him.

Question

Is there a better way to make a monk a better grappler?
Can I get advantage on Athletic checks somehow, without party assistance?