I am not certain exactly what you meant by the expression “constantly checking and re-checking” the words and actions of others. Does that mean that you are questioning them about what they’re saying? Are you attempting to ensure that what they’re saying is accurate? It would’ve been helpful to have had a more thorough explanation of what you meant by that phrase.
Your inability to trust may be your way of attempting to protect yourself from being hurt. It seems as though you are constantly in a defensive mode. Individuals who are characteristically defensive often are that way because they don’t like to be wrong. Being wrong, in their mind, might equate to being “no good.” They don’t take criticism easily and feel as though it is an affront to the core of their being.
At the heart of the problem may be a lack of confidence. If you don’t feel good about yourself, then what others say about you may be perceived as an attack. This hypersensitivity to criticism may be part of the problem.
This problem is “severely hindering your life.” For that reason, I would highly recommend counseling. You stated that you do not want to “make a big deal out” out of this problem but left untreated, you risk ruining every important relationship in your life. Without those relationships, you will be unhappy. You may only need a few counseling sessions to adjust your thinking. I hope you will consider counseling. Please take care.