Dear Laura,
I think understanding your cycle would be the best here.
I assume you did not breast feed because your cycles have resumed.
Before the menstrual bleed there is ovulation, when a mature ovum is released and available for fertilization. The ovum lives up to 24 hours. If there is no conception the endometrium that has been built up for implantation to support the baby is no longer needed and it will be sloughed off after about two weeks. From ovulation to menstruation is a very regular part of a cycle. The irregular part of the cycle is from menstruation to ovulation. The length of time here can vary and this is what can make some cycles shorter or longer.
In your case after giving birth it takes a few cycles to resume normal cycling. Sometimes unusual stress can also cause long cycles. The fact that you are not observing for the signs of fertility could certainly also mean that there is no menstruation because there may have been a conception.
I suggest you contact a Natural Family Planning teacher in your area and learn how to recognize and chart your times of fertility and infertility. In this way you and your husband can use this knowledge to choose the times of intercourse to either avoid or achieve pregnancy and eliminate taking chances and the stress of waiting!
Angie Frausto