I agree Simon. Fishy if your tank is processing the load of Ammonia you're putting in in 17 hours then it could easily cope with a couple of fish. Then you can just see how it goes.
I do know how you feel though. I have quite a stressful job and I got the tank to chill me out and give me something to do/look at now I have to stay in a lot of the week but I feel like I've had nothing but trouble with it. I'm currently having a week where it appears a load of my bacteria has died and I've no idea why. My fish had some sort of infection when I got them, one of them is dark coloured and I've no idea why, I had to take one of my fish back coz it was bullying the others, I now think I have a mild case of Fin Rot and my plants keep dying despite me dosing with really good ferts!
BUT I try and tell myself that these are teething problems and it'll all be worth it in the end. I think you will feel a lot of releif if you pack it all in but you might feel a bit of regret too. Just do one thing.....if you do decide to pack it in then keep all your stuff well stored and in good condition coz I bet within the next year you decide to try again.