First off, you have skills. You have managed tasks and assignments and, no doubt, seen them to completion. Talk with someone in your organization you respect and ask them what skills you should highlight in your resume and your LinkedIn profile. You already have a strong educational foundation so you should have obtained the core knowledge in criminal justice and security management. Sell that in your resume and when you interview.
Don't be negative about the changes in your organization – bosses will always come and go. Have you tried to identify a mentor in your organization? Look there first and if you can't find one there, look for mentors through ASIS groups, such as the Women in Security Council. Don't apply for every job that comes up. Your lack of success could suggest that there were specific skills or experience required and you did not have them. Don't set yourself up for failure by putting in for a role that would be – to put it kindly – a big stretch.
It may be time to look outside of law enforcement. Three and half years is a good amount of time and you could find a substantive junior level security role in the private sector. Use indeed.com to push job postings to your in-box. Network with members in your local ASIS chapter to hear about roles and identify employers.