I also recommend reading Brandon Turner's book (buying rental properties with no and low money down), and just continue to save as much as possible. 

People get excited about the 'guaranteed rent' from Section 8 programs, but they don't realize that tenants can lose their voucher, there is a maximum amount the program will pay based on the Fair Market Rent for your area, and that you must have a yearly inspection, even if no tenant turnover has occurred, and that it's very common to fail these inspections, meaning you have to fix things and then be reinspected in order to continue to qualify. 

I shall continue to search.

As far as the issue you might have where you may be using language in a contingency in your contract but where the contract continues regardless what happens, you need to review that with council then because that isn't really a "contingency". 

Boston continues to grow and add lots of housing.  

They cash-flow nicely are continuing to appreciate strongly and have far less to worry about in terms of tenants than my other properties. 

With my finances, should I continue to save up for a certain down payment size for a buy and rehab?

The George Lucas Museum, Coliseum & Exposition Park renovation (preparation for the Olympics), USC's continued investments in the area, LA Ram's stadium, Metro Rail development, and the fact that much the rest of Los Angeles is unaffordable, are all contributing to the development here.

Continue on or try to sell at likely a loss?

You should continue inspecting regularly (3-6 months depending on quality of units and tenants).