You cannot get pregnant from fingering yourself, or masturbating.

You get pregnant when a male sperm enters your "vag" and successfully fertilizes an egg (see links).

Masturbation cannot impregnate you, as long as you rr anybody else who touches you down there, has no sperm on their fingers--though even then the chances of becoming pregnant are very low.

(And I once made the same mistake in thinking that because I masturbated I would surely get pregnant, until some kind folks set me straight on the matter)