I spoke with my lender who got me my original mortgage and asked if this would be a possibility and he basically said no because I don't make enough money anymore, so this is the reason why HML would be my second option [I was working full time when I got my first mortgage, then I had a baby and was a SAHM for 8 months and have been working only 2 days a week since October]Any advice?

Baby Boomers are a massive generation and Social Security helps pay rent for a lot of them, in some ways it's a version of Section 8 housing but obviously with different tenants. 

They recently had a baby. 

I am a newbie looking for my first deal (a duplex, triplex or fourplex), and I had the epiphony last week that every time I buy a home to live in, I should be applying the same strategies used on real estate investing on my own personal residences.My wife and I are getting close to upgrading to a new residence (baby #3 is on the way).

Not stare at your baby face lol. 

She was a teacher before our babies came.

The only problem is she is 3 month pregnant and eventually she wont be working due to the baby.

Ok, I will feed you baby bird. 

We have about $20,000 in student debt from both my wife and I, have $1,500 in savings and have a baby girl due to join our family at the beginning of July (she will be our first and we are so excited!).

@Frank Molinaro Here is my "starting up" collection: Read http://greeneincome.com/index.php/2018/10/29/ideal-vs-desperate-investor/ Read Dave Ramsey book "The Total Money Makeover: Classic Edition: A Proven Plan for Financial Fitness." and complete the baby steps there.