If you're familiar with the Jewish blessing following a meal involving bread, you almost certainly know the phrase (Biblical verse) וְאָכַלְתָּ וְשָׂבַעְתָּ וּבֵרַכְתָּ (ve-ah-khahl-TAH ve-sah-VAH-tah oo-veh-rahkh-TAH...) - and you shall eat and be sated, and you shall bless (G-d)...
To say I'm full, as in I've eaten enough, is אֲנִי שָׂבֵע (ah-NEE sah-VEH-ah) for a male and אֲנִי שְׂבֵעָה (ah-NEE sveh-AH) for a female. Or, you could simply say, שָׂבַעְתִּי (sah-VAH-tee) - literally, I've become full.
The word is not related to the word for seven - that's with a שׁ (sh), not a שׂ (s).
How's your Hebrew?
If you haven't yet gotten your fill on the Hebrew language and would like a nice boost (or a starter), consider Ulpan La-Inyan: