Had cleaning at dentis she told me to floss and my recding gums won't get no worse?

Possibly: Receding gums can be caused by inadequate cleaning leading to periodontal disease and loss of tissue attachment. Other causes for gingival recession may be due to overzealous brushing and/or habits such as smokeless tobacco usage. You should have regular visits with your dentist to monitor your periodontal status.

Sounds Possible: If your gums are receding because you're not flossing, then, obviously, flossing would be very helpful. However there are other causes of gum recession which should be ruled out as well. In either case, though, flossing is helpful in a variety of other ways. So, even if flossing doesn't help with your gum recession, you should be doing it anyway. You can only benefit from flossing. No down-side.