Don't despair. It took me 90 hours to get my PPL(A). Then I went on to get a PPL(H), CPL(H) and instructor's rating. Ages afterwards I mentioned my 90 hours to an airline pilot, who said some people take well over 100 hours, but are still reasonably good pilots at the end of the day. There are all sorts of reasons, and you've identified two - your long breaks and your difficulties with navigation. Well, you've started having more regular lessons, and the nav problem is overcome-able (is that a word?).
I'd suggest you try another instructor, even if just a couple of times. You don't know that it's you, not him. I kept thinking it was me, and looking back, most of it was the instructor! It's hard to see straight when you're a student who's got used to one instructor. Try it; what harm can it do, and a different point of view is always useful.
Good luck. and when you get your PPL....you can buy a GPS, and not worry too much about basic nav.
