When it comes to serving God, the fundamental question isn’t, “was it enough?” The question is, “was it what God said?”
I think we all struggle with wanting to know if we are doing enough in all areas of life. That nagging doubt is really just a peak at our limitations and the desire to exceed them. However, when we try to do this on our own and under our own steam we end up making our work an idol. However, if we remember that obedience is more important than our sacrifice we can understand that God will do more with our little than we can do with our lot.
A great example of this is the boy with his fish and bread that Jesus multiplies to feed thousands. We don’t ever need to worry about whether or not what we are doing is enough. We just need to do what God says. So pack a lunch and see what God does.