Welcome back to the forum.
This question is one that can be accurately answered based only on the title, without looking at anything else. "Are HIV tests conclusive at 12 weeks?" Yes. Always, no exceptions, no matter what the specific tests are.
And there are no medications that have any effect on test reliability, and that includes the modest doses of corticosteroids you have taken.
More important, we previously discussed your abnormal obsession with all this and the likely benefit of professional counseling. "Even my husband thinks I've lost my marbles!", you wrote, as well as your understanding that "I may need to speak to someone." All I can do at this time is encourage you once again to follow that inclination. Clearly your fears are not going to go away with repeated reassurance by me or anyone else. A good first step would be to speak with your primary care doctor about it.
In your last question you stated your awareness of the MedHelp policy about a maximum of 2 questions every 6 months on the professionally moderated forums ("I posted a couple of days ago. I know this is my last question that I can ask"). This now being your third in 6 weeks, we'll have to ask you to not post any new questions for another year. The purpose of the rule is to prevent domination of forums by anxiety-driven questions, much like yours.
These suggestions, and even enforcement of the rules, stem from compassion, not criticism. I genuinely wish you well and hope you can get beyond your fears and have a happy holiday season with your family.
HHH, MD
I wish you and your family a happy holiday. I do need help. I'm not sleeping or eating and can't think rationally at this point. I will talk to someone