They're growing up so fast!

Britney Spears just posted this selfie of her and her sons at their favorite breakfast spot, and it feels like just yesterday they were babies and their parents were still together!

Speaking of which, Brit Brit's ex-husband Kevin Federline has been pushing to get more in monthly child support, and the pop princess is fighting back. The former backup dancer claims the $20K-a-month he already receives isn't sufficient, but the "Toxic" songstress' camp is calling his bluff.

K-Fed's lawyer tells Us Weekly he plans to depose the mother-of-two to get information on her financial status, and that his client just wants "the reasonable needs of their children to be met."

Britney shouldn't have to pay for kids that aren't hers, and he has four of them from different baby mamas!