I had a similar situation in an apartment that I was renting where somebody next door to me was excessively noisy (left the radio/television on all night on high volume, talked on the phone loudly until 1am, vacuumed their carpet at midnight etc...) and I had to involve the landlord. This guy had been living there for a long time (5+ years or so) and he and the landlord were friends, so my landlord basically told me that he wasn't going to do anything about it and that I would have to deal with the noise (incredibly irritating, but I really couldn't do all that much about it). My solution was to just move away. It sounds like you have already started that process, so just continue down that road.
That being said, it is important in this situation to recognize that your relationship with this person is that you are their "customer". They are providing you a product/service and you are paying them in return. Think of ways that you can leverage this relationship with that person to your advantage.
I would recommend talking to her about it again and to say something along the lines of
"I am sorry to bother you, but I am having trouble sleeping due to the noise. Would it be possible to institute quiet hours starting at [Insert Time Here] on weeknights so that I can be rested for my job in the morning?"
If this approach is not effective, you can come back and say something like:
I have tried to be respectful about the noise issue, but I am having trouble getting restful sleep at night. If I am not able to get to sleep at night because of the noise, I may have to begin looking for another place to live.
This may cause her to become spiteful and intentionally make noise at night so that you have trouble sleeping, or it may motivate her to quiet down in an attempt to keep your business. It is hard to say what the response would be due to a lack of knowledge of her personality.
You could also try befriending them in an effort to create a higher degree of mutual respect. Inviting them upstairs for dinner or for a barbecue in the back yard could be a good way to resolve this situation and improve your relationship overall. If they got to know you better, they may come to respect you more and at night they might be thinking along the lines of:
OP has to be at work in the morning, we should probably be a little bit quieter
OP has their big presentation at work tomorrow, she is probably stressed enough as it is without us making it harder for them to rest
etc... Now, this obviously depends on their personality and your goals. It could be a lot of work to do this just to get some rest at night, but who knows? You may gain some good friends and also create a much more positive relationship with your landlord!
It may be a good idea to also evaluate how reasonable they are being. Is this the type of noise that would bother anyone? Or is it just the type of noise that is bothersome to you? Determining this can help you to decide a reasonable approach.
In my own situation, until I was able to move away from my noisy neighbors in the apartment, I started to play some soft white noise (nature sounds, a stream running, whatever you like) from a speaker next to my bed. It was rather quiet, and I could still hear the neighbor, but it helped me sleep MUCH better. This solution may not work for you because of your tinnitus, but it helped me immensely until I was able to find another place to live.
One thing to be cautious of is that you want to be as polite as possible when dealing with this so you do not make the problem worse. Since they are the landlord, they are ultimately in control of the property. As long as what they are doing is not in violation of your contract, you may have no choice but to move away if their behavior does not change.
Final note it seems like you want to be polite and create a peaceful resolution, if you continue with that attitude, I am sure that you can both work something out.