Congrats on bfing twins! She does look a little thin, but I wouldn't say malnourished. It is good that she is meeting all of her milestones. Her poops do seem a bit infrequent, but as others said, its hard to say what is "normal" in a bf baby past one month old. If her wets are REAL wet, that is a good thing.
I would not bf either child less, but I would let your dd eat first and as often as she wants. (since you supplement your ds anyway) Giving a little formula is not a bad thing if there are weight gain issues. Do what you can to increase your supply, and always bf before offering a supplement. I would suggest pumping after every feed to help increase your supply, but I assume you already have enough to do with young twins. If you can, pump for a few minutes as soon as they go down for a nap, if they nap at the same times. You are one person with 2 young babies dependent on you, don't beat yourself up if you can't pump often.
You are doing a wonderful thing by bfing your twins. Most people would not even consider trying to. Your kids are lucky to have you.

Be gentle on yourself. It is ok to give a little formula if need be. Remember, even if your twins only get a tiny bit of breast milk each day, it is better than none at all and it means you are doing a great job!

Good luck pumping at work!!! I hope it goes well for you.