Mouthwash and breath fresheners are only temporary solutions that mask the real cause of bad breath. Also see your dentist regularly, who may refer you to a dental hygienist for a good professional cleaning and some oral hygiene tips and advice. Eating regularly is important, as eating stimulates the production of saliva, which helps keep the mouth clean. If you have to breathe through your mouth all the time because your nose is stuffed up, you'll have to sort out whatever's causing the blockage if you want to cure your bad breath. Your GP may suggest nose sprays, or refer you to an Ear, Nose and Throat consultant for further advice.
Some people worry about bad breath too much - the problem is more in their head than in their mouth.
Ask someone you trust to give you a straight answer about your breath, and if it is just your anxiety at work, try to learn a few good ways to help you relax, such as meditation or yoga.