Reading about your bad day mazzy reminded me of several bad days I've had with nav.
Took a map that was completely wrong once. One leg had duff heading, next had duff time etc. I'm not sure how nav is taught for PPLs because I've only done mil flying which is just heading times and the rest is worked out MDR in the cockpit, so this caused extreme embarrasment!
I found nav to be deathly boring until something goes wrong then it it takes some degree of skill and calmness to sort things out again as you have discovered. Nothing makes you develop that skill faster than getting lost every now and again.
I'm sure you'll get to grips with it very soon but don't get complacent once things start going well or you'll set yourself up for a fall. I found out the hard way on a GH flight with a short, two leg nav out to the GH area. Upon reaching the first turn point I realised the next turn was a completely duff heading. Couldn't beleive I made a mistake on what was probably the world's shortest navex.
Best of luck with the next trip, solo nav was a great confidence booster for me after a very shaky previous nav trip.