If you don't already have a second INT ring, I'd go ahead and pick one up for use in Abyssea. The latent is ~75% HP
before adding cruor HP buffs. Even with a 400HP Stoneskin, a decent PDT/MDT idle set, and Mana Wall/Enmity Douse, I'm still not fond of running around in Abyssea with ~800/1800 HP. Depending on what you're doing, you can potentially take a lot of damage very quickly, and in those cases, Sorcerer's Ring latent HP can be a death sentence.
With that being said, there are things you can do to improve. Your set really isn't too bad, and like everyone else, I've seen far worse.
Here's a quick checklist of things I'd work on if in your position:
1) Synthetic Atmas. If you haven't done so already, head to a Scars zone and talk to the Atma Fabricant. Based on your mission progress, you can get Atmas of Ambition and Full Moon right now. Those are both decent starter atmas for BLM. Also, visit an Atma Fabricant in a Visions zone for Atma of the Ultimate. This atma is one of the big 3 for BLM.
2) NM Atmas. You can do these with your LS or with pickups. You want to pursue Atma of the Minikin Monstrosity (from Durinn in Vunkerl Inlet) and Atma of the Beyond (from Hadal Satiator in Konschtat). These are the premier NM atmas for BLM, but there's a wide array of other atmas to hunt down for your other jobs.
3) Magian Staves. I'd work on Indra's Staff +2 and Varuna's Staff +2. They're a substantial damage increase over HQ staves, and since you've been on break, you can do some of the more annoying trials in Abyssea. With Minikin/Beyond/Ultimate, I blew through my final Varuna's Staff +2 trial on wyverns in ~4 hours when it would have taken substantially longer outside of Abyssea.
4) AF3+1. Upgrading BLM AF3+1 isn't too bad. If you have a few friends willing to help, you can knock out the feet, legs, and head pretty easily. I personally haven't started on the hands or body yet.
5) WoTG missions. If you're up to it and can find friends who also need to do the missions, there's a pretty decent reward at the end for BLM. For BLM, the reward earring can be augmented with MAB +4 (if you're in need of a 2nd MAB earring) or Macc +4 (for enfeebles) and Latent Effect: Refresh +1. The latent is active when you're disengaged, so at the very least, it's a fantastic idle earring for BLM.
6) NM drops/Dominion Trophy augmented gear. If you can/want, you can pursue some things like Goetia Mantle, Searing Cape, Witchstone, Eradico Mitts, Hecate's Earring, and a host of other things I can't list off the top of my head.
By killing NMs in Heroes zones, you'll receive Battle Trophies. You can trade these trophies to the Dominion Tactician for augmented gear. For BLM, Literae Coat is a good option. It took me ~10 tries, but I got a Literae Coat augmented with +4 MAB for a total of INT+4 MAB+7. Not bad.
***. I wrote far more than I thought I would. I hope this, along with everyone's imput, gives you a good starting point.
EDIT:
Literae Coat is augmented with MAB+4. Diamond Ring is augmented with INT+2.
There is where my standard nuking set stands right now. So don't sweat it Branwen, you're not the only one who needs to put more effort into their BLM. ;)
Gook luck to you, and don't forget to have fun!