Amber Heard's Children's Hospital Money MIA

Amber Heard vowed to stuff the coffers of Children's Hospital and the ACLU's domestic violence unit, but more than 3 months after she struck a $7 million settlement ... she hasn't given them a dime ... TMZ has learned.

Heard and Johnny Depp struck a deal in mid-August, in which he agreed to pay her $7 million. Just after the settlement she said she would give all the money to the 2 orgs. Depp then said he would give the money directly to the 2 charities and actually sent the first installment of the settlement -- $200k -- in equal shares to Children's Hospital and the ACLU. Amber was furious.

We've now learned not a penny more has gone to either organization. As for why ... we're told Heard and Depp have not signed the final settlement documents so everything has now stalled. Our sources say the main hang-up is that Depp wants to pay the money directly to the charities but she wants the money sent to her. Heard does not want Depp to get a tax deduction.

Heard's lawyer, Pierce O'Donnell, tells TMZ he expects the settlement to be signed this week.

There appears to be another complication. Heard did a domestic violence PSA in which she all but said Johnny Depp abused her. Under the settlement she's prohibited from mentioning allegations about Depp. It's unclear if Depp will now honor the settlement. A source connected to Heard tells us, "She didn't disparage Johnny directly."

10:55 AM PT -- Heard's lawyer, Pierce O'Donnell, tells TMZ, "The settlement documents are being finalized and will be signed this week. Johnny is obligated by the settlement to pay Amber, and she in turn will honor her pledges to Children's Hospital and the ACLU."

O'Donnell also says Amber's PSA -- which pretty clearly refers to her relationship with Johnny -- doesn't violate their confidentiality agreement.