How can you tell if it is God answering your prays or satan testing you?

God is so good. After all that me and my fiance been going through, I finally couldn't take it. A week ago I told him that I wanted to change my life and dedicate my life to the Lord, at first he couldn't take the part where we had to stop fornicating since this was out of the blue. So we decided to be friends. We live with each other and this was becoming really hard, so it was getting to the point where he was going to move back to his mother country and I was going to go back to N.Y. but I didn't want to do that because I love him and want to marry him. So I prayed to God, I told him this was becoming to much for my heart to take and if this is your will let it be done but if it's not please take this pain and problem from me Lord and work it out for me. Then my fiance called and said he will marry me and would turn his life over to the Lord but he want me to compromise with him. Since he always want a child and I told him before I wanted one too, he said he would change if I give him a child on our wedding day. I was happy from him to want to work things out and stay with me but then I thought would that be still considered sinning? Would it matter if we had sex one day or one week before we get married?