I have two close sisters, so I can understand how you feel about missing such important things for them. Unfortunately though, it doesn't seem like you'll be able to do either, because this is a big emotional, time, physical, and financial investment for you and YH so it's totally understandable that this would be your first priority.
Here's my 2 cents, and might give you a couple of thoughts to consider:
- You may not be able to fly after your ER due to the increased risk of OHSS, since flying dehydrates you (I travel a lot for work so I read into this before IVF #1). I would talk to your RE and see what their thoughts are.
- As PP mentioned, the graduation may be the same day as your ET.
- I wouldn't do anything during an IVF cycle that will stress you out, or give you a regret if your cycle doesn't work. I was in a friends wedding four days after my ET, and even though I took it easy and generally felt fine, I regretted it and blamed myself when that cycle failed.