You CAN eliminate fleas completely 100%, even if you live in a highly flea populated area -
When you put a topical flea product on a dog, first, make SURE you apply it correctly - to the SKIN, correct doseage etc.
Here's the thing about Advantix, it doesn't do a great job breaking the
life cycle of the fleas.
I'd use Frontiline PLUS instead, it's a complete life cycle eliminator (meaning it kills eggs and larva as well as the adult fleas, and of course, ticks too).
What probably happened is a few things - after you applied the Advantix, it killed all the
adult fleas on your dog, BUT there were probably many many many eggs still living on her AND in your carpet, furniture etc. Once those suckers hatch, boom, more fleas. Now, if it's within the time frame of that dose still being effective (like you said, 3 weeks) it SHOULD kill those adult fleas, but if you're bathing her weekly, like the package said, could have decreased the effectivness.
You won't have that issue with Frontline, it's completely water-proof after the first 24 hours and it's had a chance to dry, spread, and settle into the hair folicles.
Also, as Farley's mom said, you have to really clean your appartment well, wash EVERYTHING and not just the things the things the dog comes in contact with, those suckers jump high! You shouldn't have to go too crazy cleaning more than once though if you use frontline, anything hanging around that you don't manage to get (in addition to anything she picks up outside) will be killed once it ends up on your dog.
If you're seeing them around her eyes, you have a pretty darn good infestation. I'd switch to frontline plus- you can apply it now even though it's a bit early for another treatment, don't let her get wet AT ALL for 24 hours after and don't touch the application site. Then do all the cleaning. Re-apply the 28 days later and go from there.
Even with an infestation as heavy as yours sounds, after 3 months on a product that kills ALL life stages of the fleas, you should be flea free
You can also bathe her once per week with no issues using that product instead of the Advantix. I'd actually bathe her really well with Dawn dish soap and then let her dry 100% before applying the Frontline.
As far as the bad tick problem outside - idk Advant
ix should be repelling those and generaly does a better job with ticks than frontline. Maybe it's just the frequent bathing making it less effective in that department. See how the frontline
plus works - you may still see a tick on her, but it should be dead. Well, that was long lol, Good luck