Is it permissible for a wife to stop taking birth control pills without her husband's knowledge, given that he refuses to have children due to lacking health insurance, the possibility of his emigration, and his statement "we still haven't gotten to know each other" despite a year and a half of marriage having passed?

You are not at fault for not taking birth control pills without your husband's knowledge. Each spouse has the right to procreate, and neither may prevent or delay pregnancy except with the consent of the other. The reasons your husband mentioned for not having children are flimsy, for sustenance is from Allah, and delaying procreation for fear of poverty is akin to the infanticide of the pre-Islamic era. As for getting to know each other before marriage, nothing is permissible except what the Prophet, peace and blessings be upon him, guided to, which is looking at that which encourages one to marry her.