Has your GP ever taken a swab? If you're getting repeated bouts of urge incontinence, then rather than keeping on filling you with antibiotics, your GP should arrange for you to have further tests.
For a start there are other causes, and an antispasmotic might be a more appropriate treatment. Secondly, if you are getting repeated UTIs, then your kidneys are at a very real risk. The problem with kidney disease and infection, is that you don't get any signs and symptoms until most of your kidney has been damaged, and is beyond and real salvage.
The above are extremes, but I used them to illustrate that repeated taking antibiotics isn't a great idea.
I would personally wait until you can see your GP, as prescription of further antibiotics would require knowledge of what you have already been prescribed - the last thing you want to end up with is a highly antibiotic resistant UTI, which could happen, as if you do have a bacterial infection, the population is likely to have grown up from any residual bacteria, not affected by the last antibiotic you received for your last infection...