absence of period after childbirth

[mrscutter]

Ghost or anyone,
I had a baby 4 months ago. I didn't get a period for three months and when it came it was a normal period about 6 days long. I have not had one this month. It is 2 weeks late. I took a hpt which was negative. I am 42 years old. Could my periods be off because i had a baby or do you think my levels are low and something else is going on?