Well done on passing the Nav exercise.
Don't be dispirited at all. Some days your nav will be spot on, directly overhead your waypoint at the ETA, but somedays you'll make a mistake and miss it. It's a learning process and you'll get much better as your aircraft handling becomes second-nature and you can devote more of your attention to navigation.
My initial navigation on my Skills Test was awful! I was off track and had to correct myself (and did that wrong too). In fairness, I think my diversion was fine. But I would have been very upset had I failed the Skills Test on that basis alone because I had been very accurate on my previous cross-country flights and felt I just had an off-day on my test day because I was nervous. Fortunately I redeemed myself with my general handling and the way I had handled a genuine rough-running engine on the initial take off.
Remember it's only a licence to learn....
