Massive action on job offer

I received a tentative job offer from a federal agency on 5/14. So far I have submitted all the paperwork they have sent me. I was cleared by Employee Health for employment on 6/9. I have left a voice message and emailed HR. I have received no response. Two other co-workers at my old job have also received offers at approximately the same date.
Last week co-worker #1 received a phone call asking her to finish her paperwork.
Last week co-worker #2 received more paperwork to advance to the background check stage. I haven’t heard anything for 3 weeks.
C No communication from HR since 6/9
T My application/job offer is not advancing
F worried
A sent email to HR & left voice mail regarding what’s next
R worried , discouraged

I want to feel confident & not worried that this is going to work out in due time. HR is not perfect. Where can I look in the study vault regarding taking massive action? I am ready!