I wouldn't call 143 low at all. But perhaps my perspective is skewed because my count dropped to 8 four weeks after the birth of my first child...
I did a ton of research, on my own and with my hematologist, through my second pregnancy. He and I agreed that I could give birth safely at home with a platelet count above 50. Which is a good thing, because if I had planned to give birth in hospital, my baby would have been born in the back of a taxi on the way there (super quick labor). My platelet count (taken at a routine MW appointment about 36 hours before I gave birth) was 66.
I saw a homeopath through the latter half of the pregnancy, and took homeopathic medicines, though I can't remember what they were... Sorry. The mainstream medicine alternative would have been steroids, which I took after the birth of my first child and would recommend avoiding if possible.
If 143 makes you or your MW uncomfortable, perhaps homeopathy is an option? I don't know anything about Ferrous Gluconate, but a quick google search shows it's an iron supplement. Iron, as far as I understand, doesn't have much to do with healthy platelet levels.
If you PM me, I can send you some of the research I did when I was pregnant in 2009.