A back breaking blunder

Several weeks ago, I attached a new sprinkler line to my existing irrigation system on my flower bed out front, those couplings and corners ain't cheap, but this was ugly to look at and I wanted some way to hide the pipes.
Since the height of that bottom step is TOO HIGH from the landing, I figured I would pour a new layer of concrete over it all.
Then someone suggest that I cut a groove in the cement and run the black plastic thru a white PVC pipe like a conduit, that way if I needed to change or repair something, I wouldn't have to break up the cement to get to the pipe

I bought a masonry blade for my circular saw (ended up using THREE)

One worn down to a nub, one brand new for comparison

I am scared of saws, being a musician, so my neighbor volunteered to come over and do the cuts for me
Then using a masons hammer and a cold chisel, I broke out the concrete and formed a groove for the pipe to sit in

I didn't know how much concrete would be needed, but I knew I wasn't going to put more than 2, maybe 3 inches over that pad.
I bought 4, 60 lbs bags and rock for the finish.
My form was half assed because I was working alone.

Today I gathered my materials and set about mixing.

Friends, I have worked as a Landscape helper, and as such I have mixed MANY bags of mortar mix for brick flower beds or sidewalks, but that was half a bag of mortar mix to 12 shovels of sand.
I did not have the luxury of doing it that way, so I bought premixed.
AND I've never mixed FOUR bags at once.
I mean to tell you that nearly done me in
Beginning to thing I'd made an error, I went ahead and put the bonding agent over the old landing

And then TRIED to shovel out the concrete.
It just wasn't nearly enough

I had no help to try and screed it more level, I just had a short tooth rake and a hand float

I went ahead and flung the river pebbles I'd gotten for this very purpose. To me it looks fine, but I know it will not be durable and will break out in pieces around the edges.