Thankyou for your honest question.
All of us experience doubt to one degree or another. Ever since Adam and Eve in the Garden of Eden, the evil one has planted doubts in our heads as to the goodness and trustworthiness of God: “Did God really say…” (Genesis 3:1). Even those who directly saw the resurrected Christ doubted: “When they saw him, they worshipped him; but some doubted. (Matthew 28:17).
However, doubt is not unbelief. Doubt is a state of mind in suspension between faith and unbelief. Due to the ongoing presence and power of sin in the Christian life, which is a reality until the day we die or the Lord returns, none of us will have perfect, 100% trusting faith. Doubt will continue to be constant struggle. It is a part of our fallen nature that does not trust God with all our being. But having doubts does not mean we are not Christian. The opposite of faith is unbelief, not doubt.
Yet doubt will lead to unbelief if it is not ealt with properly. There are two errors we must avoid when it comes to doubt. The first is to be too soft on doubt. That is to think that doubt doesn’t matter, making it a trivial matter. This does not seem to be your problem. The fact that you are taking your doubt seriously indicates to me that you take your faith seriously. To overcome doubt (which will not be 100% possible in this lifetime) we must pray and cry out to God to help our doubt, go back to the bible and search for the answers to our doubt and to ask him to strengthen our faith in his Word. God is the one who gives us faith.
The second error is to be too hard on doubt. The claim that “a true believer never doubts” is false. To insist that only doubt-free faith can be counted as genuine-faith is to misunderstand sin. Doubt is not the opposite of faith, unbelief is. Doubt does not necessarily or automatically mean the absence of faith. What destroys faith is the disobedience that hardens into unbelief.
Coincidentally I am a doctor, and have spent years studying anatomy. It is quite possible to drive nails through the hand or the wrist without breaking a bone. But you don’t need my authority to tell you that. The Scriptures say so and are trustworthy.