As for the mag, I don't hear many people who talk about having had complications with, but I certainly did. The day after I was admitted they put me on it and my bp skyrocketed, my heart raced, I had trouble breathing, and I started having contractions (at 23w!). They didn't believe I could possibly be having contractions and told me I was having a panic attack, which I didn't believe because I wasn't worried until the symptoms started. I finally got them to hook me up to the contraction checking machine and they were shocked to see that I was right - frequent contractions. My mfm started to drive in to prep for my delivery and said the nurses had 20 min to get my bp down and the contractions stopped before I was delivering. Labetelol and procardia got things under control and they decided not to mess with the mag again pre-delivery. They were still claiming it was a panic attack, though. Fast forward to a few days later, after I delivered (c-section), and they decided to try the mag again. This time they didn't do the big started dose, just jumped to the lower maintenance dose. I was pretty out of it - in and out of sleeping - and had exactly the same reaction (minus the contractions since I had delivered at that point). At that point they finally believed that I wasn't having a panic attack and that my body was in fact reacting very poorly to the mag. Took 6 hours to get things back under control again in recovery. To this day no one can tell me why I reacted that way and they said they've never had anyone react poorly to the mag before like that. I'm also worried about them wanting to use it again in a future pregnancy. Glad to hear your mfm is aware of your history and listening to your concerns!
Hope I didn't scare you more, just wanted you to know that having trouble with the mag is rare but you aren't alone!