Silk felt exactly the same when I first started budgeting, and DH even more so, but over time we've found areas we can shave off a bit more here and there and have enough spare for the things we really want to do. We also sat down and (and this was really helpful, weirdly) and discussed the friends we have who seem to have a better lifestyle than us (not significantly, but able to afford the odd holiday/takeaway/lunch out/new clothes). We realised that literally all of them either have two professional salaries (we have one, plus my little bit of self employed income), parents who hand out money or probable/definite credit card debt (based on what they've said to us about money and their finances). So actually it's not unreasonable that we can't keep up with them and need to cut our cloth slightly differently. My lightbulb moment came with food shopping a few weeks ago when I was moaning that I can't get it down to a sensible level and really looked at what I was buying. I love a good mozarella/avocado/Parma ham/sundried tomato salad, so was buying those ingredients every week but actually even in Lidl they add a fiver or more to my shop. I had a real 'actually, I really like that and I deserve it, but right now I can't afford it. End of.' realisation.
Afterhought it sounds like you're doing brilliantly, well done 
Badvoc you've identified your weaknesses - amazon and eBay. I would delete your card details from both and only go on them if you need something that has been budgeted for - eg kids clothes. I used to buy a lot of kids and my clothes etc eBay, but actually I realised that I was enjoying constantly searching for new bargains and buying everything that was good value. It actually makes more sense for me to buy new and only buy twice a year or so - we take a real look at the DC's wardrobes in spring and autumn and make a list of what they need and wait for a good Boden code and order it. For me, I have a one-item-a-month limit (excluding undies and really cheap basic vests etc), so if I know I need a new jacket, I don't go out and buy new shoes. Sometimes it's an expensive item, sometimes it's a cheap one, but it averages out and I am, over the first three months of this year, on budget. It has also really made me choose which item I most want each month and build up to buying it and enjoying it.