Absolutely. Postpartum depression/anxiety by definition can be diagnosed up to a year after your baby is born.
Postpartum depression (and anxiety) is one of the most common complications of childbirth, affecting about 15 percent of all new moms. For many, symptoms start a few weeks after birth. This is why your obstetric provider should screen for it at your six-week postpartum check-up. However, some women find that their symptoms show up much later, and by definition postpartum depression/anxiety can be diagnosed up to a year after giving birth.
Therefore, if you are concerned that you might be experiencing depression or anxiety, even if your baby is a few months old, be sure to get in touch with your doctor or midwife so they can screen you and recommend treatment if necessary. Luckily, almost all women with postpartum depression/anxiety can be successfully treated with therapy, medication, or a combination of both — and both your baby and your future self with thank you for caring for yourself enough to get help.