Why were you told to wait?!

Janna • Mom to angel twins born sleeping at 18w and a chemical baby. RIP Maven and Macie and Littlefoot.
Seems like we've all been given some different answers as to why you should or shouldn't wait to TTC. I thought it would be nice to see all the reasons we've been given so we can all decide what's best for ourselves. (Forgive me for not putting 100% faith into doctors as I once did)
If you feel comfortable, I think it would be helpful to share a little background as well so we can find people similar. 
I lost my twin girls at 17.6w when their hearts stopped beating. A week earlier I had surgery to try to fix TTTS (a disease that only affects identical twins). Obviously, it did not work. I was induced and gave birth to my daughters at 18w.
I actually had a team of doctors due to the twins and TTTS and one doctor told me as soon as I stop bleeding (2 weeks) and another told me to wait 3 months but no one gave me an actual medical reason why.