Hello adventurer!
You must be quick to get your blood back, at start you only get 1-2 of blood if you win an encounter, but have in mind that depending on the combat, the enemy can damage you so if you start a combat with 10 blood units, and the enemy does you 3 of damage and you win, you will end up with a total of 9 blood units.
I hope this is clear, cheers!