I think you don't need to worry about the tithing - give to God and His work what you want to give. The New Testament doesn't push the tithe. Jesus came to set us free from the shoulds and should nots of the Old Testament. Now He wants us to know He already has paid the debt for your sins - there is nothing you need to contribute. He wants you to know Him and love Him.
As a result of this blessing of life give you, you will want to give to His work. You want the gospel to reach as many people as possible. You want to give, not only in money, but in time, and with your skils.
So, now you need to plan that there is something first to give to God before the whole check into direct deposit. If there really is nothing left, you may be able to offer your time - teach Sunday School, sing in the choir, clean the church bathrooms, etc.
Hope that this encouraging for you.