I'm not discouraging you from taking the progesterone that you have. You mentioned the cost so pregnenolone is a nice alternative to try. It might have some additional benefits for brain repair.
We see in the HM detox groups that people with bad cases of AI/AF, pregnenolone and progesterone don't get converted well all the way down to cortisol, aldosterone, etc. These people often report that low dose hydrocortisone or similar helped quite a bit.
I'm also not discouraging you from working with your doctor. I usually suggest that people get followup testing and work with a doctor. it is sometimes quite tricky to balance hormones as you'll read in our group.
Preg and prog each have some of their own effects as well as feeding into the pathway for downstream hormones. This seems to be especially true for women!
A close female friend with low cortisol almost all day on 4x saliva cortisol test actually responded better to pregnenolone + progesterone cream than she did to 15mg HC. She gained a strange 15 lbs on the latter. Preg + GABA/glutamine turns on her brain wonderfully without the weight gain. She still uses 5-7mg HC as well.
Adrenal cortex glandular is sometimes also used but may not work for your budget. I would not expect it to replace HC for bad cases of AF.