whats up marquiese! you might not even know what house hacking is but what you are doing is called house hacking and it is a great way to build wealth in real estate! I would definitely hold onto the 2 family and let the rent cover your mortgage as you build equity in the property while the property appreciates overtime. once you have 20% equity in the property you will no longer need PMI. Maybe by the time your daughter is ready for college that 2 family can pay for her schooling + more.
regarding next steps in buying your next house for you and your family. I would definitely start talking to lenders and a realtor ( me ) about lending programs and what you can afford. I assume you have great credit due to you paying off your debt so quick. The debt from the 2 family shouldnt hold you back if you can show it is being rented. theres so many different routes you can go like the traditional route or take advantage of some MA home buying programs. we would need to talk further to see what fits you best. any questions feel free to reach out. Good luck!
