After trying to buy a home in Boston a few years ago, Jenny and Jorge Fortin paused to regroup. Competing with higher bids and all-cash offers, and not eligible for other down payment programs because they earned too much, the couple concentrated on building their savings.Then last fall, when Jenny’s mother became ill, they decided it was time to find a house for all three of them, plus Jenny’s younger brother. “When mom was hospitalized, we decided to check out Landed’s down payment program,” said Jenny, who previously worked for the City of Boston. “It was also a good time because we were getting married.”