Hi! I have had that same experience with P4, so not sure if it means you need more or not, but it would seem to indicate at least that it's dropping...i had very low temps this cycle, and also a shortened luteal phase and I had my P4 checked and it was only 1.9, but that was 2 days before AF (but it was 7 dpo!!)...(I didn't take P4 this cycle because my temps were so low I couldn't even determine if I ovulated or not...my baseline yesterday confirmed that I did because I have a CL cyst). I only mention this becuse my coresponding temp was way below the coverline on this day so that too made me wonder if all the other low emps meant my P4 was low on the other days, even at 5-6dpo. I can't remember, did they check your P4 after O? I think so...I have found that some cycles mine seems to drop off dramatically based on my temps, even with the P4. I wonder if they do additional checks, or just give you more P4? I did a LPD panel once where they take your P4 and E2 every other day starting at 7dpo through 11dpo once and it showed normal levels, but each cycle can be different so I just don't know. I don't think I helped you any, but if you find anything out I'd be curious to know:)
My guess is that if you tell the nurse tomorrow you want to do IVF, then you just tell her and they will start working on getting you ready for it. I believe that's all that Mrs. McIrish had to do (I remember she too was wondering about it a few weeks ago) but she can speak better to this than I can. I think moving to IVF is a wise choice, good luck!