Hi there
Firstly, you will be able to bring yourself to inject so don't worry! I found that the first injection was by far the hardest just because it's something new. Plus, it's a bit of a surprise how tough the skin is when you're trying to pierce it. Just make sure you have a death-grip on your stomach and don't hesitate and it's a piece of cake.
I found I didn't really start to get bruising until I started Puregon, and the Puregon pen was quite awkward, but you'll find a way of using it that's comfortable for you.
I felt a bit lousy on Puregon but I over stimulated (30ish follicles), but was fine on Buserelin - thankfully, I didn't have any trouble with headaches. But, drink lots of water, that'll help regardless, and especially if you have headaches.
The last few days before EC were hard and I was finding it very hard to move, but then I was chocka block with follicles (20ish of them were on one side) so that might have just been me! But, plan on needing to take it very easy before and for a few days after EC.
I hope that helps a bit, but if you have any other questions, just fire away
There is another mum on the boards donating eggs, but I'm not sure if it's common knowledge or not so I might PM her and give her your name, rather than put it here. All the best! I really admire you doing this voluntarily!