Hi lakshya14.
I don't think the issue is that you are "overthinking" the answer choices. I think the issue is that you are relying on "techniques" that don't really work rather than analyzing the relationships between the passages and answers choices and using basic logic to determine which choices answer the questions.
There are many recommended techniques for answering Critical Reasoning questions that don't really work because answering Critical Reasoning questions takes reasoning, of all things, rather than the use of a gimmicky technique.
So, probably, what you need to do is adjust your approach to answering Critical Reasoning questions and handle them more as you would had you never learned any of those "techniques."
For instance, if you are answering a Weaken question, you could view the argument as something that one person has said to another person and consider which choice the second person could bring up to call what the first person said into question, not because some technique points to that choice, but rather, because common sense or logic dictates that that choice brings up a consideration that truly serves to call the first person's conclusion into question.
If you handle Critical Reasoning in this way and really learn to see the logical relationships between what the choices say and what the passages say, you won't overthink anything. In fact, if you are answering a well-written Critical Reasoning question, generally, there is no way to overthink. You will either see what's going on or not see it. If you don't see it, you won't choose the correct answer. If you do see it, no amount of overthinking will stop you from choosing the correct answer.