I think you should make clear what is the thesis statement of your essay in the introduction, you can state what migration you mean (urbanization?), what is the difficulties of living in the city and the government policy. If you choose urbanization, you should consistent.
In the second paragraph, the terrorist attack is too far. You could explain what is the difficulties of living in the city, not the impact of migration to the city. For example, The first difficult for migrating people is difficult to find a job especially if they just have less experience ... Second, the living cost is high...(explain why) Third, reason 3...
In the third paragraph, you should explain the government policy that makes the urban life better for everyone. It is better if the policy solves the difficulties you mention. In addition, you should make it clear who is the "everyone".
In conclusion, please restate your opinion and highlight the reason.
I hope it can help you.