Ask yourself this question: "Am I convinced that God will answer my prayers?" Being convinced leaves no room for doubt. I'm not convinced if I am 99% sure. I am not confident if I think it might not happen.
Faith is being sure of what we hope for; certain of what we do not see (Heb. 11:1). If you have doubt, then you are working from a potsition of "hope" instead of "faith". Hope leaves room for the possibility that your prayer may not have been heard. "I hope God hears me." That is how most of us pray, I believe.
It is beyond our ability to be "doubtless". We are human and we are flawed. We require the Holy Spirit of God, Himself, to help us believe and not doubt. We have to choose to seek Him and His righteousness. Sound familiar?
Read Matthew 6:33:
"But seek first his kingdom and his righteousness, and all these things will be given to you as well."
Have you ever considered that our faith grows when we actively seek Him?
Makes sense...the more you know Him, the more you know what He is capable of, the more you will trust and believe in His power and willingness to answer prayer.
How is your faith? What are you actively doing to seek God and His righteousness? Are you a person of FAITH, or simply someone who HOPES? According to James 5:15:
"The prayer offered in faith will make the sick person well." May God empower all of us to truly be convinced that He hears us and wants to change our circumstances.