Putting Drills (both at home & at the course)

Happy Monday (only 5 more days till grind time again! Hang in there!),

I'm here today to ask for some feedback / tips on some in the home putting drills and on the course putting drills. Let me give you a little bit of my backstory to explain the absolutely need to change my putting game:

It's my second season as a dedicated player to the game. I hit the range normally 3-4x a week hitting about 150-200 balls each sessions, and on the days I don't hit the range I work on bettering my impact with irons and chipping in my apartment, hitting into a net. This practice in my irons / driver / fairway metals has taken me from a 22 handi to a 12, which I'm extremely proud of due to the amount of work I put into my game.

What I'm here for is I feel I could be a single digit handicap if I could get my flat stick in check. I average about 12-14 3 putts around.. 50% of those being bird looks that turn into bogeys (trust me, it's more painful to deal with than to read about I'm sure). I just happen to have one of the best rounds of my life (79! from the tips at my club). What was the difference? Only one 3 putt, and I hit almost every 5' putt I had. I don't know what I was doing differently with my stroke (I tried to consciously take notice throughout the round) but nothing. I'm dedicating all of May to my flat stick and getting it in check. I've documented my flaws with the putter since noticing it was what is crushing my scores. My problem is not the line ever - it's pace, pushing / pulling putts .. and even sometimes hitting my putts 'thin'.

Now - I live in the city, so the range I go does not have a short game area, so the only putting I can work on an actual green doesn't come till I can make it to my club Saturday and Sunday. Are there drills I can do in my apartment to help work on some of the issues I have (pace, push, pull, poorly struck putts)? I have a pretty big apartment so I have room to work. Also, any tips I can work on at the course I would greatly appreciate.

TLDR; Putting is causing me to shoot in the high 80s and playing to a higher handicap than I should. I have poor judgement of pace, I push / pull putts, and I strike my putts poorly more than I hit clean square ones). What drills / tips could I do @ my apartment t o work on this and drills I can use when I'm at my club?

Thanks!