if you get a bump after an insulin injection it means that you chose a poor injection site. Insulin absorbs into subcutaneous fat. So wherever you shot and a bump comes up, that means there was not enough fat in that spot to absorb the insulin you just shot.
try picking a more fatty area and shooting very slowly.
You can also get lumps from injecting at the same site too many times.. keep changing sites every three days you should be good.