The explanation that popped into my head:
She is nursing and has to go out for several hours. She milked herself for Discord to feed their child while she is busy and is completely irrationally worried that three bottles won’t be enough. Discord is about to grow a green-with-purple-polka-dots Cow udder with three teats to assure her that it couldn’t possibly be an issue.
Possible, but I think it more likely she is… well, read my previous comment if you haven’t already.
Edited because: Rephrased for increased politeness.
Perfectly acceptable.
That reminds me, I finish that lads request.
She is nursing and has to go out for several hours. She milked herself for Discord to feed their child while she is busy and is completely irrationally worried that three bottles won’t be enough. Discord is about to grow a green-with-purple-polka-dots Cow udder with three teats to assure her that it couldn’t possibly be an issue.