Hi Camille,
@Camille Joos-Visconti
It sounds like you have made solid financial and lifestyle choices in your purchase and owner-occupation of your triplex. Not only are you building considerable equity, but you also created a a positive living situation for your immediate family and father-in-law.
The encouraging news is that Burbank and Glendale feature some large 2-4 unit properties with one of the larger units often featuring a 2-3 bedroom unit (often detached SFR). Just yesterday, I visited two duplexes in the Magnolia Park neighborhood in Burbank that featured a spacious 3bd/1bth homes and a separate 1bd unit in the back. (in the prime Roosevelt elementary school district) These specific properties were not on the market, but there is certainly similar housing stock in the Burbank and Glendale areas if you are interested.
Burbank and Glendale are strong investment cities without rent control. Please be warned about investing in the mult-family Los Angeles city market with rent-control. There are certainly good opportunities in the city of Los Angeles, however, too often buyers are not properly educated or misled by their real estate agents about rent control. (The lack of education about rent control amongst real estate professionals is astounding.)
If you and your husband don't mind living in a multi-family, I would strongly suggest keeping your property and purchasing another multi-family featuring a larger unit for your family (and rent out the other one, two, or three).
Or, you could sell your current property and buy another larger multi-family property for you to reside and rent the other unit(s). If you were to sell your current property, you likely could take out some cash tax-free since you owner-occupy a percentage of the property (assuming that you have lived there at least two years out of the last five). This can be a huge plus if you buy another property that requires some work since you could tap that cash for rehab. You would need to consult a tax professional for specifics but you have some intelligent options with a 1031/tax free cash-out situation.
My wife and I lived in owner-occupied Burbank triplex before we moved to our SFR. We still own the triplex. I highly recommend "House Hacking" --as long as both spouses are on board!
Best,
Jason