C.W.
When I got the Mirena removed, the following week I got this horrendous week of bleeding and I had no idea if it was a period or not. The Dr said it wasn't, just that it was hormone let down. Anyway, I conceived right away and had no idea when the due date would be because I hadn't had a real period. The dr was amazed that I conceived so quickly, he said it should have taken a month. Anyway, I miscarried. From what I have read, it is really a good idea to wait to conceive until after you have a true period after the Mirena removal. As for conceiving the boy, I can only give you my personal experience which probably doesn't match up with others. When conceiving my son, sex was probably day 1 of the ovulation timeframe, and it was missionary style (sorry if TMI, but position is important). For my daughters, it was more like day 3 of the window, and the position was not missionary.
Good luck!