I use the spray all the time, not cause of particularly hideous breathe but because the one habit I really really miss is chewing gum! I've had boots own, awful, and mccleans which isn't so bad. Not had the strips cause I don't like them, check the pack for carbs, they might be ok.
I ordered some listerine strips last time I did this, and still have most of those left. I didn't get the bad breath until about 1 month in last time (my husband keeps me informed!) and it hasn't emerged yet this time. I am pretty sure last time happened because I wasn't drinking enough for a couple of days.
I chew sugar-free gum once or twice a day for about 5 minutes ( just when I fancy it) - sometimes more. SnS recommend that you can have up to two sticks and chew for up to 60 seconds. It affects people differently I guess.
Bear in mind that the bad breath is due to ketones being released. If you drink more water more ketones will be released through your urine and there will be less to leave via your breath. As always don't drink lots of water all at once though as it is dangerous.