Only Nagato have high reserves for an Uzumaki as he is of Senju descent. Kushina had special(chakra chains I think) and strong chakra. Naruto's chakra is cause of kurama's mixing together with his own.Strong and large are different terms buddy.
Their chakra were potent but they never had large chakra reserves.
While senjus and uzumakis have large large chakra reserves E.g. Tobirama, hashirama,kushina and naruto