Hi! So glad your son is doing well. Sounds like you are too. It looks like we delivered within 6 days of each other gestation-wise. I had HELLP too.
First off, I had blood testing before I got pregnant again (actually it was done before I left the hospital when I had my son), and the only thing that turned up was MTHFR, and it's not the worst type. That's probably half the reason why I'm on extra folic and baby asprin. Otherwise, I've taken that plus lovenox injections purely just because of history of pre-e/HELLP/pre-term birth. The science isn't really strong saying these things help, but some doctor's are for it. We also suspected a luteal phase defect with me which messes with implantation, something that might be a pre-cursor to pre-e. So I also took supplemental progesterone at ovulation and continued that to 8+ weeks.
I'm 31 weeks today. I also haven't seen the MFM yet this pregnancy, but I consulted with him before. He recommended a plan in agreement with my OB, and my OB doesn't treat me like a normal patient. He consults with the MFM, sees me frequently, and I go to a special room for high resolution ultrasound at every appointment. If I had anything show up suspicious with growth, blood flow, protein, BP, fluid, or anything - he'd refer me to the MFM for a second look, but so far all has been completely normal. You mentioned monthly appointments... I definitely think that's going too long, especially at 22 weeks. The longest period between appointments that I've had is 3 weeks, and that was at 14, 17, and 20 weeks, where the risk of miscarriage or pre-e is low. I'm now at 2 weeks and will probably go to 1 week pretty soon. I had some swelling in my ankles around 26 weeks after some shopping and a road trip, but my doctor wasn't concerned because it can be normal, it's not in my face and otherwise I'm healthy. It went away and hasn't returned. It is good that you're having your BP monitored weekly, but I'd want growth, fluid, and blood flow monitored at least every 2 weeks from now on out. Maybe your OB could up the frequency, or put in a referral to an MFM to see you every other time (they each see you once a month or so, but you see either the OB or MFM every 2 weeks)?
They should be very understanding about doing whatever to calm your fears. You don't have a long rapport with them and you've been through a lot! My OB just told me he'd think I was nuts if I wasn't at least a little anxious about this.