Many mortgages have a clause about an issue with locking in anything more than 2-yr terms so I don’t offer more than that.

Best options would be a local hard money or private money lender.

After the last refi the new mortgage loan was $170k and sold the house for $270k so I thought I was going to owe on a gain of $100k but she says I'll owe on a $180 gain because she's calculating on all 3 gains. 

I've bought properties, gotten private lending and have built up contacts in my phone for a bunch of investment friendly contractors, from people I've met at those meetings.  

The combined value of the three rentals is $1,500,000, with remaining mortgages totaling $290,000 (with 12 years left), leaving me with $1,210,000 in equity.

I have never gotten a residential loan before, all the mortgages I currently have on the multifamily properties are commercial loans. 

I wanted a place to live, but I also wanted help with the mortgage so I have two renters that pay a total of $1400.

Without question the Pandemic fueled activity and mortgage rates drove investment and inventory of STR's and vacation rentals for rent up in many destination markets. 

I listed my expenses above: mortgage/taxes/insurance, management fee.

The answer is yes and no.The reason I say no is that most mortgages will have a clause in there allowing the bank to call in the loan if you transfer your interest in the property.the reason I say yes is that most of the time, they don't bother with this.