Random bleeding between periods…

I had a baby 16 months ago. I got my first period 8 weeks postpartum. I’ve been pretty regular until about April. I started having irregular periods. One month my cycle was 35 days the next month it was 25. I would experience some light spotting off and on between. Or light bleeding once and then not again for several more days. My son is starting to wean from breastfeeding. Some days he nurses 2-3 times and others only once. And never for very long. Trying to figure out if the bleeding could be caused by the hormone fluctuating because of the breastfeeding changes or if it could be something More serious. And should I be seen by my doctor? If anyone has experienced something similar I would be so grateful to hear your thoughts. TIA