You should feel reassured in that you have a Lord who is just. Allah, the Exalted, admitted a woman into Paradise because of a dog and another into the Hellfire because of a cat. The first was a prostitute from the children of Israel; because she once gave drink to a thirsty dog, Allah forgave her and admitted her into Paradise. This was a just recompense for her sincerity in doing a good deed, for her sincerity to Allah. The second was a woman who confined a cat to a room. She neither fed it nor gave it drink; by confining the cat, she prevented it from eating insects in the fields, and so Allah made her enter the Hellfire.
The story of the first woman is one that brings coolness to the heart, because it makes one know that Allah gives great rewards for small deeds.
(So whosoever does good equal to the weight of an atom [or a small and shall see it. And whosoever does evil equal to the weight of an atom [or a small ant] shall see it.) (Qur'an 99: 7-8)
(Verily, the good deeds remove the evil deeds [i.e. small sins].)
(Qur'an 11: 114)
So help the grief-stricken, give to the poor, aid the oppressed, visit the sick, pray over the dead, guide the blind, give comfort to the afflicted, guide the misguided, and be generous to both guest and neighbor. All of these are deeds of charity, deeds that not only help the receiver of your kind acts, but that also help you by giving you comfort and peace.