Re: Working part time, supply dropping, supplementing now?
Most moms stop pumping at a year, so that is an option if you are interested. At this point your supply is firmly established; enough that it is there when you need it. You are not going to dry up completely from not pumping during the day, particularly if it is only 2 days a week.
If you continue to nurse 3-5 times per 24 hour period you do not have to replace the breastmilk with any milk alternatives, though cows milk is perfectly fine after a year old if you wish to introduce it. Especially for good solids eaters, most can make it through the day on food and water (or occasional juice if you want) and just nurse when they are with you.
And of course if you wish to continue providing breastmilk, that is fine too. Four ounces is a pretty fantastic output, especially at this point (many women start to struggle with pumping output starting at about 9 months on). There is much less worry about sending 'enough' for the reasons I mentioned before, so there is no need to be concerned if it continues to drop.
“We are not put on earth for ourselves, but are placed here for each other. If you are there always for others, then in time of need, someone will be there for you.”