I installed white porcellain 12" tile in my house a number of years ago, but it was over 2 layers of 3/4" CDX topped with a 1/2" cement board all screwed down well. I used the Mapei thinset and Mapei sanded grout, pretty sure the thinset was latex modified can't find a left over bag of it right now I thought I had.
You will want to follow the directions exactly even though it might not make a lot of sense- mixing several minutes with a drill/mixer, letting it sit for like 5 minutes then mixing for 2 more.
Best use a good 3/8" drill and a jiffy mixer and have a spare just in case, the stuff gets real thick and it's a bit of a challenge for a drill.
I'm very happy with the products I used and there has been no cracks, loosening or failures, not even with heavy dogs playing or rolling heavy sculptures over it on a handtruck.
One last thought- get a tile cutter like I did, one with a diamond blade cause porcellain is so hard you really can't score/break or use regular ceramic score and break tools, at least mine didn't work, so I bought what looks like a mini table saw with about a 5" blade, for wet cutting tile and brick, I think it was about $65 at Menards, a cheap piece of junk but since I only needed a one time thing I bought it for this, it lasted longer than I needed to cut tile for 3 rooms and a hallway, and the included blade lasted that long and will still cut too.
Use hearing protection- cutting the tile is ear shatteringly loud, and eye protection, do it outdoors is highy recommended!
Broken tiles everywhere--tile cutter would break about every other tile.
If you were breaking every other tile with that tile cutter, why didnt you stop and examine WHY the cutter was not working right? This reminds me of guys at work around machines that start making bearing burning out squeeling noise or malfunctioning, instead of turning it off and getting me, they keep using it till it seizes up or BREAKS! odd/excessive noise, vibration or results not expected are a warning flag, it means STOP! look, examine, find out why something has changed, correct that and then continue.
Breaking every other tile is a red flag that something is not right, either the cutter, the tile or your technique, if you had stopped it would have saved you frustration and a lot of money.
I tiled 3 rooms and a hallway in my house, I don't remember breaking any tile. If you used porcellain tile and tried a score and snap ceramic tile cutter, there's your problem right there!