Poppy, have your pcp/gp refer you go a urologist. There are some good medications that may help in this area. They will likely also send you for urodynamic testing and a cystoscopy because incontinence can be associated with retention, which can cause an increase in bladder infections, plus there a few other non-neurological things to rule out.
The stress incontinence is the initial leak. The bladder emptying (which I've also experienced but thankfully not for a while) will require a medical professional to evaluate.
Additionally, Tena is your friend ... ;)
Forgot to add, make sure you don't have a UTI of some sort which can really escalate things.
Helen I'm so sorry your dealing with this.....I personally deal with incontinence issues but i haven't actually experienced 'stress incontinence', which is generally a very common female issues as your probably already aware.......for women because pregnancy and childbirth weakens the pelvic floor muscles that support the urethra activities that push down on the bladder eg coughing, laughing, sports, sneezing etc can cause urine leakages.
Menopause can also cause stress incontinence but it's because of the reduction of oestrogen and oestrogen basically maintains the thickness of the urethra lining, and gets the urethra to seal after you've passed urine, not enough oestrogen, giving birth and your plumbing is likely to go faulty on you.
I would recommend you look into the stress incontinence behavioural training techniques to see if pelvic floor strengthening exercises, changing to more frequent routine toilet brakes etc makes a difference. One trick that sometimes helps is to make sure you are actually emptying your bladder, after purposefully urinating instead of thinking you've finished, you relax and wait for a little while and then you try to urinate again.
I would of sworn i wasn't retaining urine but i habitually do this little trick with my bladder issues, and it still surprises me the amount of urine that usually still coming out with the 2nd and 3rd try lol hot weather and it doesn't work because my bladder seems to have lost it's stop function, so it's like someone didnt bother to turn off the tap and out it trickles...
Incontinence information:
Basic information -
http://www.continence.org.au/pages/how-do-pelvic-floor-muscles-help.html
Various pdf worth looking at -
https://www.thewomens.org.au/health-information/continence-information/urinary-incontinence/
Video explaining kegel exercise -
http://www.webmd.com/urinary-incontinence-oab/video/corio-kegels
More informative but has research reference lincs
http://www.australianprescriber.com/magazine/37/1/10/3
Hope that helps.........JJ
Thanks for your comments Aspen and JJ. I got totally drenched today but thankfully it wasn't due to my bladder LOL. Will be interesting to see what happens next time we have a roasting hot day.
Although I'm not certain my whole problem is stress incontinence I will investigate the exercise thing.
H