Welcome to the forums.
Answer to your question: Yes. You can (should) walk and chew gum at the same time.
Slightly seriously, I sense that you want to gun for "brand name programs," which is why you want to retake your MCAT. Goal should be +10 from your first score, so 519+. If your practice tests have been this high, you should retake. Give yourself enough time to prepare properly.
You definitely need more experiences, especially service orientation. In-person experiences where you are comfortable with uncomfortable people in a humble role, not as a subject matter expert or "leader." You must have 150 hours when you submit; if you're going for brand-name schools, you must have 250 hours. Crisis text line is not face-to-face experience. With zero hours currently listed, your application may be summarily screened out.