I have a constant fear of kufr thoughts and actions. I really want to be a Muslim, I know that Islam is the truth, but with every thought, every thing I say and every action I do, I'm afraid that it might have been kufr.
Sometimes I know it's just waswas, but other times I'm not so sure. And then I spend a long time thinking about what my intention was when I thought or said that thing..
My questions are:
1. when I'm in the process of thinking about if something was kufr or not, and then for example my parents want to talk to me, is it kufr to stop thinking about it

All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad, is His slave and Messenger.

This is nothing but mere Waswaas (satanic whisperings) that is unreal. Thus, you have to ignore it, pay no attention to any of it and believe with certainty that you are a Muslim, all praise be to Allah, and that you do not go out of the fold of Islam based on such delusions.

You should repel such thoughts and refrain from considering them any longer. If your parents, or either of them, call you while you are having these thoughts, then repel the thoughts immediately and answer your parents. If no one calls you while having these thoughts, then you should also discard them as quickly as possible and not dwell on them any further because they are from Satan. You will be rewarded – Allah Willing – for striving to repel these whisperings and endeavoring to discard them.

We ask Allah to bless you with wellness.

Allah Knows best.