Just my thoughts take them as tiny grains of sand:
There are many types of progesterone. There are oral pills, vaginal pill suppositories, vaginal cream suppositories (of different strengths).
For me, I had a short luteal phase, would start spotting about 6dpo, would have full blown period by 8 or 9. My doctor prescribed oral progesterone. I was SO excited. It was so frustrating when it did nothing. I did some research on my own and asked for the vaginal suppositories, and was denied.
When i finally got to a specialist who I had a good relationship with (we listen to each other, both ways), they agreed. I got on vaginal cream suppositories called Crinone. This helped, but still wasn't enough.
I ended up on a combination of 200 mg prometrium (which is the oral one) 1x a day Crinone and 1x a day another vaginal suppository that was higher.
It took some trial and error, but I am 100 percent confident that it made a HUGE difference for me. Once we had the balance right (which was judged by various bloodwork and transvagainal ultrasounds at 10-11 dpo to see the type of endometrial lining) I was pregnant within 3 months.
Unfortunately I miscarried at 7 weeks (unrelated). Devastating as that was, it's still wonderful to know that I am capable of conceiving.
There are a lot of conflicting opinions out there on progesterone (and well, really, on EVERYTHING fertility related, lol!). But I am a strong believer in the importance of vaginal suppositories and the right balance. It's not always easy to find doctors who agree.
In my personal (not a doctor) opinion, if you're spotting at dpo 4, you need more progesterone. (not necessarily more orally though)
But perhaps more importantly, I understand how frustrating it can be when you think you've finally found something that can help, and it hasn't made a difference. Don't give up. Progesterone CAN make a difference. Sometimes it just needs some tweaking.
Good luck!!!!