Welcome to the forum!
If she's going backwards-try to see what's changed in your routine. Perhaps your trusting her and letting her go longer between potty breaks?
First and foremost, if she's had an accident it's extremely important to clean the area really really well. They have great noses and the slightest smell of urine/feces will let them know that it's an OK spot to use. Rent a steam cleaner or use a shop vac and hot soapy water if the accident happened on carpet. Then use baking soda to deodorize
For puppy training, punishing especially after the fact does not work (Not saying that's what your doing-just a tip
) If you catch her in the act, scoop her up, take her outside and when she resumes business praise her.
Set her up for success.
Take her outside after every meal, after every playtime, after every drink, when she wakes up, before bedtime, and about every 1.5-2 hours. If she doesn't 'go' when outside don't worry-But when she does-praise praise praise. Try to put her in one spot to do her business so the spot will 'smell' like business and help her associate that it's the correct area.
Remember-for pups, they can only wait at most, about one hour for every month that they are (as a guideline) so an eight month old puppy may be able to last the whole day while your at work for a typical work day. A four month old pup can go four hours at most
So eleven weeks-she should go out every two to three hours at least