I had this with dd1 too. Dd2 is 8 months old.. My skin is always best when pregnant!! Some days it's fine, then most it's acne, and even on my chest and neck too now as we'll as my face.
I know I need to eat more nutritiously and drink more fluid but I just forget whilst having two of them!
I take pregnancy re breastfeeding vitamins, and also perfectly for my skin.. I have only had two periods since having dd2, which started about six weeks ago. So hormone build up maybe?