Brittany Renner Asks Court To Increase P.J. Washington Child Support Payments, 'At Least' $35K

Brittany Renner wants a court to increase P.J. Washington's child support payments to her -- saying in a new filing this week $5,500 a month is just not enough.

Renner made her case to the judge in documents that TMZ Sports has obtained ... asking for "at least $35,000" a month from Washington in an effort to raise their 4-year-old son in a manner suitable to a kid with such a rich father.

She claimed in the docs when she and the NBA player first agreed on the $5.5K number, they lived together in North Carolina -- but things have drastically changed since she and the toddler moved to California late last year.

Renner said she "cannot afford the high cost of living given the current child support orders" ... and she added that with Washington exercising "less than 1/2 of the visitation time he is entitled to" -- she's now "struggling to make ends meet."

"I cannot provide [our son] a life anywhere similar to that of his father," Renner wrote in the documents.

Renner noted Washington -- who just recently signed a new, four-year $90 million contract extension with the Dallas Mavericks -- lives a life of luxury with his wife and their children. She said they "have multiple luxury vehicles, constantly post their designer shopping clothes, and boast about luxury vacations."

"They also constantly post their children wearing designer clothing," Renner wrote. "In contrast, I live in a humble Airbnb rental in West Hills and shop for [our son's] clothes at Target."

In addition to the $35K a month, Renner is also asking Washington to pay her attorney's fees, which total $50,000.