Hiya. Your English is pretty good, but non-native. You need to work on having cultural fluency as well as having linguistic fluency. Americans and, in particular, Americans with hiring authority
do not respond well to excessive modesty. You should stop saying things like "I have to admit that I am not the smartest person" and "My brain has been dumb for several years."
Saying things like this will make Americans with hiring authority think that either you are being sincere and are stupid (no hire), that you have severe personality issues which will make you difficult to work with (no hire), or that you are culturally inept and will be difficult to work with (no hire). There is a fairly easy way to avoid these difficulties: find a model of culturally correct behavior and act like they do. Your model person would likely a) be confident that they are well-qualified with regards to what they want to be hired to do and b) not brag excessively about their competence. Don't worry about where the exact balancing point between confidence and bragging is -- any attempt to move closer to it will make you more successful at locating employment than you are currently.
Also, getting employed is a matter of selling something (selling your future employers on the notion that they should employ you). Successful sales is more about them and their needs than it is about you and your story. Your relationship with your parents, your home culture, the laptop you bought, etc, do not constitute reasons why a particular company should hire you. You should not talk about them. Instead, you should figure out what the company needs and point to specific, identifiable experiences which demonstrate that you will successfully be able to meet that need.