If I get your question right, you've fallen into the same trap many other native Russian speakers had before you. The way we've been taught English at school was "non-standard" in many ways. One of them was: "I/we should", "he/she/they would". Perhaps, it was a norm some time back, but these days "should" means "должен" almost in all cases. And "would" is used with I/we as well.