I had this problem when I started on a pump about 5 years ago, and after the first one, everything went downhill from there. I had another one a month or two later, and then another one a month or so after that, then one after a couple of weeks... up until just before I came off the pump when I realised the insulin wasn't delivering as soon as I changed the set. I had to give myself a break from it (and just started back up after 2 years about 2 months ago. Having no problems at all now) because I was so covered in scars and lumps and I felt as if my body was just trying to fight any intrusion off. Looking back on it now, I was taught to just "clean the cannula site before insertion with soap and water" whereas in America they're taught to use antibacterial or antiseptic wipes (or whatever they're called) so I asked if I could do that this time around (they didn't recommend it because it could toughen your skin but I figured if they're all doing it in America without complaining of skin problems, why not try it and find out?) so I do that all the time now. I also changed from the quick-sets to the mio infusion sets because the quick set insertion device was AWFUL- the stickers would always get stuck and it wouldn't go in right which would result in bent cannulas. I've not had this problem with the mios, and I like that because it's a new inserter everytime, you don't have to worry about whether the insertion device is clean. Also, looking back on it, I think I should have avoided the entire place around the previous infections- the first one I got was on my left leg, and I think I should've stopped using that leg completely for at least a couple of months to allow it chance to heal properly. That may have prevented me from getting further infections.
The best advice I could give you would be to go NOWHERE NEAR the previous infection sites with your cannulas for a good few months, and only do set changes just before a meal if you can- the biggest problem I found was that when I did the set change, I wouldn't know if it was okay until giving a large dose of insulin. The basal insulin went in too slowly for the pump to notice it wasn't delivering, and I found that I'd only realise it wasn't working either if I gave a dose of around 10 units of insulin, or if I tested my blood sugars and they were crazy high for no apparent reason. By that time, the infection would be needing treatment because the lack of insulin caused it to develop very fast, and I'd become more insulin resistant so it wasn't until getting antibiotics that I could really get back to normal.
Hopefully in your case, you won't have any more trouble anyway! Good luck!
) and I'm doing fine 
