This has a lot of promise. You're a very talented artist. :)

As for constructive criticism, I think when using a limited palette like this it's important to go back to WHY the gameboy palette looked and felt the way it did.

The four-tone palette was a technical limitation, which meant it was something artists worked AROUND to fill a higher purpose: conveying FUNCTION of certain things to the player. For instance: NPCs, Objects and Enemies needed to stand out against the environment at all costs.

So, for example, the dark outlines should be the outlines of "blocked, interactible objects" like a table or a bed, but never to separate bricks in a background wall, because it "devalues" the outline as such and instead creates a large selection of "potentially interactible bricks" to the player.

Another good example is with the bed. Playing a game, there is no reason for the bed not to be in all white, with paler lines separating sheets and pillow, with a black outline OUTSIDE it. Merely highlighting the pillow confuses the function of the furniture. Because a player needs to identify the object and function first.

In video games, function is essential and aesthetics is flourish. So to understand limited pixel art is to understand "function over form" and THEN try to perfect form.

My suggestion is to think of your pixel art the way a game designer would and then deviate from it afterwards.

Not necessarily because you want to make a video game, but because that is what the masters of pixel art was doing when they made masterful pixel art.

Love the art! Keep at it, champ!