How good am I at piano?

There is no way to know unless you show use some pieces you can play. Either way, it's still to early. These things take time. Don't expect it to come with a few years of scales and arpeggios.

I too am self-taught and I've been doing it for over 17 years. Without a good teacher I'm still lacking in the advance piano playing. All scales and arpeggios do is help develop technique and know your way around the instrument as well as speed up learning new pieces.

Try playing/practicing 3 different pieces each week, if you don't finish, just move on to the next new 3 pieces you haven't played before. If it's difficult find something that is easier so you can polish up your techniques. Scales are about developing your technique correctly through repetition and multiple keys but aimlessly playing through them will learn you bad habits.

Listen to others playing: professionals, recordings, armatures etc... Rather than slavishly copy what you hear try to listen to yourself and change things you don't like so instead of just mindlessly practicing music play small section and be picky about how a note sounds; does it need to be lighter or louder? does it need to be held back or released quicker? Are you pressing the wrong note without noticing? Are you using the pedal correctly? (When the pedal is depressed, you should not press it down fully but just a little or before half-way so it doesn't smudge everything and make sure notes at slurs are shortened slightly and staccato is noticeable with the pedal)

You are a beginner. You will always remain as a beginner unless you have some piano lessons. Because you haven't had any lessons you will be doing lots of things wrong. These things that you are doing wrong are what will stop you from ever being anything more than a beginner. It is quite likely that when you go for lessons you will have to start again so work out what you want to do. If you want to get better and move to an intermediate level then go for some piano lessons. If you don't mind remaining a beginner with lots of faults in your playing then you don't need any lessons but you will never get to intermediate level without the lessons.

What you're describing sounds more advanced beginner than intermediate to me, but if you want, post a video of your playing.

You'd have to share a video with us. It's not only about what you play but how you play it.