Is it bad to drink when you're on your period?

You should avoid drinking during your periods. Your body is fatigued and already experiencing a lot. If you drink, the chances for a heavier flow increases and will make you more uncomfortable and uneasy. So, try to avoid it.

you had periods right after your delivery? what was the date after delivery when your period started?

Toddler at 14 months can only say monosyllables like ba ba, da da, ka ka. So you need not worry.