Don't beat yourself up over it- WI will be what it will be, and if its up then you will be a bit more tougher on yourself the next time life throws somthing crappy at you- but dont be upset or worry.. there was no point synning (tehe) if you wernt enjoying it. So i hope, despite your bad back you enjoyed indulging in some naughties whilst you rested up.. and will just have to throw yourself back into some superspeed next week.
Every week makes a difference, but sw is for life.. so in the grand scheme of things, this one week wont ruin it.. will it? You can do this xx