Reflection - When will I know the truth?

As I go further into my studies I can see contradictions to my previous learning. This has led me to question the truth behind the information I call knowledge. What I learnt yesterday is contradicted by today so what I learn tomorrow in university show me a new picture again. And which picture should I trust- the simplistic one I saw as a child or the new one? these questions have put me in a dilemma and my reason seems to be failing me.
Where does knowledge come from? How is knowledge attained? Do we tend to oversimplify the Ways of Knowing? Do we believe in science, and how much do we believe it? There are many sources of knowledge throughout the world that communicate to people about what events that have happened and what is happening at this very moment. However may lie or are misleading, have bias, and come from different perspectives. Being misleading, having bias, and having different perspectives with in a source make the sources harder to be considered trustworthy. . Not all these sources can be trusted. Which one should we trust? As a TOK learner I am trying to find answers but the more I try the more I obfuscated I get.
I always believed that history was written based on biased perceptions and manipulated by those in power. But I always believed that science and mathematics to be absolute and true. But lately my beliefs are changing. In the ICSE I was told that Watson and Crick discovered the DNA double helix model and received a Nobel Award for it. This was written in Biology textbook. After coming to the IB I learnt that it was actually their assistant Roselyn Franklin who made the discovery but died soon after and the two scientists took credit for her discovery. Also in ICSE we learnt three Laws of Genetic Inheritance by Mendel’s that governed the inheritance. However in the IB I learnt polygenetic inheritance that gives a completely new picture of how the Human body actually functions. Everytime I learn something new I have to revise previous knowledge claims; this means I never knew the truth. The revised version I know today I think is the truth but is that so? In math I was told that the root of negative numbers does not exist, in the IB I learnt that the root of a negative number is an imaginary and denoted by the letter ‘i’. Today I do not know the value of ‘i’, but will I know tomorrow, does it have a value or no, if no then why am I using it.
Thus there have been many questions lately that have perturbed me. All I can say is that we never really know the whole truth, but we must acquire as much information as possible and then only make a knowledge claim. One book or any one source for that matter is not full proof. Counter arguments need to be considered and related areas have to be analysed.