No expectations

I think when we give we need to examine our hearts and our motives. Do we think God is a bank account and He will return financially more than we have given. It is true that He will always provide. Also that we reap what we sow: "Do no be deceived. God can not be mocked . A man reaps what he sows. Whoever sows to please their flesh, from the flesh will reap destruction. Whoever sows to please from the Spirit will reap eternal life."
To me (and I am not a bible scholar) I see many meanings from the scripture. If you do not sow anything into your garden you will not have produce or "fruit." God looks at your heart motive with your sowing (how man used to make money and eat). If it was for all the "flesh" ways of this world you will reap destruction. But if you are sowing to please God guided by His Spirit leading us to give, we will reap eternal rewards.
This specific scripture does not promise a reward on earth. I have heard this to be true with missionaries who give so much of their potential finances in life and always struggle financially. Yet God always provides for them and even at times blesses them unexpectedly.
My own experience has been that God has blessed me more than I have blessed and sometimes before or after a blessing. I admit I have struggled with an unpure heart motive but it only made me miserable. It was like trying to wrestle with God. Releasing things to God makes life so much easier!!
Blessings
The gift giver