Just wanted to add that I am TOTALLY sympathetic to your situation... it took us over a month to get Oscar to a pretty reliable place where we weren't leaping up off the couch in fear every time he sniffed the floor!!
We got him at 8 weeks, but we were pretty beside ourselves for about the first month because it did not at all seem like he was "getting it", even though one or both of us was home with him ALL THE TIME, and we took him out every half hour to an hour! He seemed to get
BUT -- it DEFINITELY gets better!!! And you will be SOO happy once it all clicks
Here's what worked for us (others have said these as well, but just my 2 cents on what ACTUALLY seemed to work for us)
1) Constant vigilance!
2) A crate!!!! (or two, like us!) We put him in there for his naps during the day, and always gave him something nice. Oscar cried and cried for the first few weeks when he knew we were around, but eventually he loved his crate.
3) Setting a timer for 30-45min between potty trips. (We wouldn't wake him up if he was sleeping, but we always took him out once he woke up. Also before/after meals, after playing... pretty much after everything he did!)
4) We live in an apartment, so we CARRIED him outside to his potty spot (to avoid accidents in the hallway). Outside, we say "hurry up!" and then say "good boy!" quietly as he does his business, then lots of praise & petting and a treat(s) when he finishes. He figured out the benefits of pottying outside VERY QUICKLY!
5) However, Oscar did not really seem to catch on that going INSIDE is not good (for a WHILE), so whenever we "caught him in the act", we would say "AH-AH! NO!" loudly, and if he stopped, picked him up right away and go outside. Usually he did not stop (even if we picked him up, I think they just really CAN'T stop peeing because of muscle control!), so we would pick him up when done and go straight outside. The other person would clean up the mess in the meantime (so he didn't see you), or if alone, would put him in his crate once back inside (so he didn't see you clean up). (I heard that they would figure out peeing gets attention if they saw you clean it up?? don't know how true this really is but we did it anyway).
6) When we were getting REALLY frustrated, we decided to stop giving treats during his other training throughout the day (e.g. sit, lie down), and ONLY give treats (multiple!) for going to the potty OUTSIDE. Our reasoning followed the "cashing in his pees & poops for treats" mentality that I read somewhere (maybe on GRF???)... if he "knows" he can get treats for other stuff, he has less motivation to really "hold it" until he gets outside... This might sound really crazy, but it DID really seem to help -- maybe just coincidentally LOL, but I suspect we were probably just giving him too MANY treats for various things throughout the day, which reduced the interest/novelty of his "potty" praise/treats.
7) And last, we found out just recently that Oscar has a bladder infection, which was obviously negatively impacting his bladder control as he had just started to have accidents in his crate (which had not really ever happened before). So if you really suspect that your puppy "should" be able to hold it for a certain period of time and he is still having accidents (although this does NOT apply to an 8 week old puppy, who can only hold it for 30min-1 hour, if he has had water recently), make sure you talk to your vet because there might be some health issue confounding your efforts.
Best of luck!!!!! You & your pup will surely persevere!