<p>No, you should keep the verbs in the past tense. One of the problems is "has felt", a better choice would be "felt". I think that is important to be grammatically correct when you use the third-person narrative. In your dialogues, you could have errors to reflect the way the dad and Sebastian spoke. </p>
<p>You may want to rewrite the sentence, "The last week has felt longer than his eight years." I hate to suggest anything because it is important to preserve your own voice, but "the last week had been the longest of Sebastian's short eight year life" might read a bit better. I'm sure that you will find an alternative sentence that is even better. </p>
<p>In "His daddy and him were poor", you have to realize that "Him" is a subject in the same way as "He" in "He and his daddy were poor." </p>
<p>Read your essay aloud and some of the little errors will jump at you. Good luck.</p>