I agree with all of you regarding the metronome. At first you will hate it because you are forced to play at a regimented pace. It forces you to be accurate in your melody. It is a Godsend for proper timing especially when playing rolls and sets of triplets. I have an electronic metronome on my computer and I use it every day. The results are definitely paying off as I now notice that my note values are more even and I don't rush a set of triplets anymore. Everything seems to flow more evenly. The metronome is a must if you want to get serious about playing any kind of music on any instrument.

And .. If you'd rather not purchase a metronome,
there are several 'virtual' online metronomes
that you can run with your computer.

You don't even need to download them ..

--bn

Luckily I have at least 2 metronomes on my iPhone alone and they work really well so I will definitely get in a habit of implementing it.

A lot of good advice from the Braves...how lucky we are to have such a board....left hand was a struggle for me too....I was told to keep playing it..no matter what...and it will come along with time....just like wine..it gets better with time/age...one thing I did, was played in front of mirror....as you know the motion of the bass side for waltz and 2 step...when I see my hand playing it, it sorta help me...if it did not look right I corrected it...but listening has more to do with that, you know when it does not sound right...anyhow good luck to ya and stick with it...it will get better with practice..practice...practice...

When I was a kid I learned to play piano-accordion.
It started with simple children songs and it's easier to manage the bass-side if you keep the melody simple. After some time it becomes an automatic thing with your left hand.
I don't need a metronome, because I'm one myself who drink to much