If it's a male you're going to have to give him a place where he can hike his leg. It's normal for males and he will "miss" most any paper or square you put down.
he's already learned someone's "method" and yours is different. This is what I posted for someone else (changed a bit for you) -- but I never try to "schedule" (taking them to elminate at specific times) and I *never* leave them in a crate when I'm at home - they need to be with you and learning. I do crate when I'm gone, but not when I'm home unless I can't supervise.
There are many different "styles" of house-training. I would simply let him drag a leash 24/7 until you have him trained. Why? Immediate control!
I would slip that leash over your belt. I never "schedule" altho many dog. I don't think they go by a clock -- they go by how long stuff has been in their bodies - they go after a meal, after sleeping, after playing ... but not really a "clock".
From the sound of what you're saying it almost sounds like he could have a UTI (urinary tract infection) -- particularly if he doesn't fully 'go' or if he goes a bit, walks a bit, goes a bit more. Now, he's also fast approaching the age of sexual maturation so he's also likely far far more interested in marking and claiming territory than a younger pup.
The very first thing I'd do is take him to the vet - you need to have a fecal done anyway, and have the vet do a urinalysis (not just a 'strip' test - you need to rule out things like crystals, etc. that could make it painful to fully drain the bladder) and rule out anything medical first.
As far as training goes -- 'Scheduling' IS easier. But my way is to simply leash them to me and *watch* them like a hawk. You watch for them to stop, look or sniff around for a place to go. Then, you say "gotta potty?" and ZOOM him out the door. He's on leash -- you *can*.
When he's outside -- just focus on "potty". Then - don't let him play .... ohhhhhhhhhhhh noooooooooooooooooooooooooo. He's there to potty. That is **all**. You stand in that spot where you want him to go and wait. No playing. No butterflies. No fun. You just wait for him. Then .. if no production in a few minutes (this is NOT an hour-long drama here) you go back in and resume.
over ... and over .... and over. Eventually he will 'go' while he's out there and then you can have a party. You can then allow him TO play outside as a reward! All the while convincing him he's the best danged boston ever!
IF he has an accident in the house. Go put him in his crate (not punishment -- just a holding place for him while you clean up.). I don't really know why, but I've always found it somehow rewarding for a dog to see you handle their waste.
But go sop it up with paper towel, and take that towel outside and lay it where you've been wanting him to go.
Then go get him -- zoom by the "scene of the crime" and just say matter-of-factly "Not there! Not IN the house!" and proceed directly outside saying "OUt" as you go out and to **the paper**. The dog sniffs it and you say "Yep! It goes OUT here!"
He'll get it -- the fact that you will **move** his waste tends to help that lightbulb moment.
Now remember you have to clean that spot SO well -- they can sniff their own scent so easily.
See I want to know when they have to go out. I don't want them to just "happen" to go while we are outside. I want them to understand that walks and playing are one thing. But potty is a whole different ballgame. And when you do it right great things happen.
Once he *begins* to get it you can drop the leash and let him drag it. But honestly -- it is SO handy and so much easier to re-direct them and keep them from screwing up when leashed it really really helps.
My whole theory of dog training (and this extends to many many things) is to simply make it nigh onto impossible for them to screw up. With the leash I can ensure they do **everything** right. And they get used TO doing it right and hearing praise for that. It is so much easier to stay positive when you can use a leash and literally **avoid** a lot of mistakes.
I hope my Americanisms haven't confused you -- good luck. And you are a very wise person to seek help so soon, rather than get frustrated!