Why Do I Keep Wetting Myself?

Hi There,
Firstly, well done for having all the basic tests done to exclude any obvious causes for your problem. This sort of problem is not caused by weak pelvic floor muscles and it really needs a full investigation to find and treat the cause.
Your symptoms do sound very similar to a UTI (urinary tract infection) and it is definitely worth going back to your doctor for repeat urine tests and further advice. Sometimes a test can come back negative even when there is actually an infection. There are many reasons why you might get a false negative, such as: if your urine is very dilute – a positive test relies on a specific concentration of bacteria to be present in the urine, or the specimen may have been left in a warm spot, or contaminated at the time of sampling, or the bacteria responsible for the infection cannot survive in the open air, to mention just a few.
Other conditions such as thrush can sometimes also cause urgency and burning sensations, so ask you GP for a swab if you think this may be the case.
More rarely sometimes very tight pelvic floor muscles or muscle tightness associated with anxiety can trigger similar symptoms and a few other conditions can give you similar symptoms.
Please go back to your doctor as soon as possible and keep going back until they can give you an answer to explain your symptoms. Sometimes a GP will prescribe an medication to treat a UTI on the basis of your symptoms if these are severe.
In the meantime: Restricting your fluids will make the symptoms worse, so drink enough water to keep your urine pale. Try a half teaspoon of bicarb in a glass of water, 2 to 3 times a day, to reduce the acidity of your urine – this will help reduce the burning sensation. Then speak to your doctor again as soon as possible.