I worry (a lot) when I think (of other girls) about how they (shine) sparkle and radiate beauty and about how I could be (brighter)
(and) nothing hurts worse than thinking about not being with (you) my love, my heart because I know you (deserve the) best, you are my (sun), moon and stars
Notice the parentheses. Read the poem all the way through, read the parentheses next, then finally just the words outside the parentheses.