I'm a newbie myself, searching for my first deal - but I am running a lot of numbers recently.
If I understand correctly you are building a home for yourself that is actually a triplex, and renting out the two other units for $600 each?
Plus renting your parents' old home for $1k.
First, I would suggest analyzing the two properties separately, as you really have two completely different deals. That will give you an idea of the return for each property.
Keep in mind there are a lot of costs other than just the mortgage cost. You have taxes, insurance, repairs, capex, property management (even if you do it yourself, pay yourself!), & vacancy/credit loss. Those are all going to add up to significantly more than $200/month.
For people to be able to help you with the numbers, do you have the following numbers:
Parents house:
current value, estimated repairs needed to rent, estimated monthly rent.
Your new house:
What is an estimated rent for the main unit that you will be occupying? Without knowing how much of the value is derived from it vs. the two basement units, it's hard to tell if they are worth it.