It's gonna be a bit before I have number 5, but I'm fertile like you too, 2nd, lol.
Pregnant with my 1st 10 weeks into a new relationship. Pregnant again when she was 6 months old, but lost the baby. Pregnant again 5 weeks later, but lost that baby too. Pregnant with my 2nd by my daughter's 1st birthday. They are 20 months apart. Then there's about a 2 year age gap between my 2nd and third, but only because my ex had a vasectomy and I didn't get pregnant until we split. But I used a sperm donor for her, had only one donation and got pregnant on the first try. My ex and I got back together and he forced me to tie my tubes after my 3rd was born. As soon as I could, I started paying off a $5800 surgery to untie my tubes when we split again. I had my tubes untied September 24, 2013. Ovulated October 27, 2013. Did donor sperm again with the same donor, and got my BFP on November 7, 2013.
Not even tying my tubes and untying them stopped this fertile one, lol. Can't believe my baby will be a month old in a few days. Goes by so fast. I think I will go for number 5, but because I had an emergency c-section, I was told to wait and let my body heal for at least a year, so I'm gonna do jut that.