When I had gaps in my resume, I always said I was "working on personal projects" during that time :-) You could explain your 16 months that way. What one person hiring thinks/believes and what their company quotas or needs are, etc. isn't the same as another; I'd try several more times until you find a job. It can often just be clicking with the interviewer enough and could be you're "out of practice" with interviewing, and more interviews will get you back up to speed so you can land a job.