Hey, I've played through this campaign a while back, and I really enjoyed it. Easily one of the best Freespace campaigns I've ever played. A few missions gave me a LOT of trouble (not that i can remember the names of many of them at this point) and I wound up lowering the difficulty for many of 'em.
Right now, I'm replaying it, and JUST passed The Adhara Exodus again. Thankfully this time, I managed to do it on my second try, on Medium; Medium's my default difficulty for most campaigns. Last time, I'm pretty sure I had to lower the difficulty to easy or very easy...and even then, it was close IIRC. It often feels like some of these defense missions rely a lot on luck, sometimes the target you're defending gets through okay, other times it just gets annihilated and it feels like there's little you can do to prevent it. In the Adhara Exodus's case, I can usually do well and keep the Damascus up to 60-80% integrity until near the end, where the final few waves of enemies come in, one of them being Taurvi bombers. This part threw me off the first few times as at this point, the Damascus would get utterly obliterated, and I couldn't figure out what was doing so much damage to it. Certainly not the larger, slower Shivan bombs that you can shoot down. But this time, I realized they were firing much smaller, faster missiles at it that were doing like 5% damage a pop. At least, I think it was the Taurvis that were firing those? I think there were 2 or 3 Taurvis left, I was facing the Damascus and trying to figure out what was damaging it so much, and saw those flying into it from behind me.
So maybe not so luck based after all, just gotta figure out what enemy wing is shooting those missiles... Haha, truth be told I'm not the best FS player, maybe because I don't use the mouse for movement...Ever since I was a kid, I always played using the numpad. Mouse movement lets you aim easier, but it also makes it much slower to turn around, at least for me, even with the sensitivity at max.

Never had a joystick either..
Anyway...phenomenal work on this campaign, again, it is a joy to play. I read in a post up above you're making a sequel?