Breast engorgement

So my little one is just over 3 months and for the longest time I would only wake up with only one breast engorged (left side)as he sleeps through the night for me (has done from about 1 month old). The last week or so I was waking up with both breasts engorged (I was verry surprised)

My period has also returned this week(heavvyyy)! Now this morning woke up with only the one breast engorged (left side) again. Is this normal? Has this happened to anyone else?