S.H.
Many hugs to you....know that it's good that you posted this here.
DO NOT give your baby milk! A baby should not have milk until 1 year old. AND it has to be "whole" milk.
FIRST, make sure your baby is getting enough intake, not getting dehydrated, and is making enough wet/poopy diapers. Then, do you KNOW for sure that this is affecting your milk output?
Next, is your baby gaining enough weight/growth per his well-baby check ups? (he must have had a well-baby check up at 9 months old, right?) If not, and his weight is not gaining and/or he is losing weight, it may be affecting him, and he may not be getting enough intake.
Next, how is your baby? Is the "stress" affecting him? Meaning, is he crying or getting fussier etc.? This "might" mean he is not getting enough intake as well.
Are you nursing on demand and at least every 3-4 hours? You STILL need to do this... direct nursing is the best way to insure that your body will make milk and aide in production. Nurse him at night too, even if he wakes in the middle of the night.
And, I'm sure your baby is eating solids? But still, for the first year of life, a baby's primary source of nutrition is from breastmilk/formula.
Next, STILL take your "pre-natal" vitamins... this helps with lactating Moms. My OB/GYN ALWAYS has his patients take their Pre-natal vitamins as long as they are breastfeeding. No matter how long that is.
Next, eat well balanced-- eat protein, you need the iron. Eat calorie dense foods like peanut butter. Eat carbs, this will give you energy. KEEP hydrated as well, drink lots of water.
Don't skimp on foods or calories now, since the stress is affecting your weight and milk output.
Next, DO check with his Pediatrician and tell them about what you said here... see what they recommend. Or, see a Lactation Consultant. If you DO need to supplement your baby with Formula... then do so. There are many different brands/types... and some babies will not take one, but will take another. SEE what your Pediatrician says.
Next, see your own Doctor.. and see what they can recommend. Just be sure NOT to take anything that you don't know about... because anything "not good" can leech into the breastmilk and affect your baby.
Take care and all the best...
Susan