Lovebird will NOT stop screaming!

Hi all,
I'm new to these forums but I have been a bird owner for about 10 years. I own two cockatiels, and my roommate has a lovebird, Squirt and a cockatoo. She is about 4 years old, black masked, and absolutely will NOT stop screaming. We have tried just about everything either of us can think of at this point. This includes:

Rotating/rearranging toys
Putting new toys in the cage
Giving her extra attention
Letting her out to just climb around on the cage, etc.
Covering her when she screams for about 5 minutes and then removing the cover
Ignoring her when she screams
Giving her LOTS of attention on the rare occasions she is not screaming
Putting her in with other birds, or putting other birds in with her (She then proceeds to attack them)
Giving her a nesting box (so far she has only ever been quiet when she had eggs, but obviously we cannot keep HER eggs with her forever, and she will not accept dummy eggs)
Giving her treats when she is quiet
Trying to "out-scream" her
Changing cages
Teaching her tricks
Putting her in different rooms where she might feel more center-of-attention
Probably a few other things I have forgotten by this point in time.

At this point, we are seriously considering finding an aviary of some kind to take her, because we absolutely cannot stand it anymore. It is constant, grating, and I have never had this sort of an issue with a bird. Even our cockatoo is not this loud! As I mentioned, we cannot put her with another bird because she attacks every one she meets (she even attacked the cockatoo). She also bites people, and will go after you even if there is a toy in your hand for her (will reach around the toy just to bite YOU instead). She is not afraid of people, she was hand fed and purchased as a baby. I don't WANT to give her away, but we are at our wit's end, of sorts. Does anyone have an experience with this and/or any suggestions we may not have tried? We are quite literally going crazy >.>

How long have you had her?
Could something be disturbing her, did you move her cage, get a new animal?
New hairstyle?
Have you checked her droppings? Are they normal in size and color?
Could she be sick?

I am probable not much help, but I owned a pair of lovebirds when I was young. One past away, the other became very hostile. Much the same as you, i could do nothing with it. Constantly screamed, hated me, hated everyone. I had rehomed it thinking it would enjoy some avian company. The new home had to keep it far away from the other birds, it literally wanted to kill the other birds, it didn't matter if it was a lovebird or a grey.
Some people have told me this is not uncommon in lovebirds that loose a mate, it was many many moons ago, I was maybe 19-20 when I gave it away.

When Lupita's eggs didn't hatch, she went off the deep end a little. She started pulling out beakfuls of Tito's feathers. I separated them and now there is no bird with her because Tito died and Rita has PBFD. No advice, just a thought that maybe birds are like people, they just go kinda nuts sometimes. Sounds like you have tried everything, maybe try to find someone with an outdoor aviary?

Sounds terrible. I can imagine that you don't want to give it away. Maybe placing it outside? Maybe it needs a change of scenery. I've been a bird owner for only four months but I could only imagine what you are going through. my lovebird is quite something, he's super sweet at times and at others he's a pain in the A**.
Just try the change of scenery, maybe it's sick.

Have you tried taking her to the vet to check there is not an underlying problem causing her to scream? I only say this, because sometimes there can be a hidden problem with animals, and the screaming (or in other animals other repetitive behaviour such as circling) is the externalisation of that problem... even something like a nutritional deficiency or a hormone issue. If she was happy when she was on eggs, perhaps try the vet before rehoming?

I would suggest foraging activities and exercise via flight... Heck, maybe even a large cage that she could fly in moved to outside for some supervised time outside????

There's also the option of introducing safe, fresh branches from outside full of leaves for her to destroy?