Great job. Doing way better than me! You're definitely like 85% there or something. I don't know exactly what standard you want to get your singing up to but what's for sure is that you have gotten all the hard, important stuff out of the way.

I don't really know for sure since I'm not at your level but I think if you went through and practiced this phrase by phrase and just focused on increasing the precision of getting the sound you want in small segments like that and just repeat that micro-managed kind of practicing a bunch of times, you'll probably be able to work some more polish into the muscle memory so there are less minor errors when you sing it all the way through

Great stamina, a lot of us would have to sing this lighter to get through it

Quentins points are spot on I think

Also almost more important than your singing here is getting the production down. I think you should maybe add a subtle chorus effect and definitely a nice full sounding reverb, for that kind of prog sound. And get the vocals fading out with the track at the end.

Adam Mishan said
The quick fix is bring the volume of the vocal down 3-5 dB and throw on a medium-large hall reverb on the vocal and adjust to taste to give it the illusion that it was recorded in the same space as the instruments.

Great advice overall but I think 3-5 db would be way too much. I think lowering it about 1-2 db will be the right balance.

Some good references for vocal volume setting I use are:
-listen to the quietest phrases on headphones, bring the vocal volume down until you start finding it hard to hear the lyrics then gradually bring it back up until you can just barely hear every word clearly if you concentrate on it

then from there check the loud parts: listen on speakers and if any of the belty parts jump out in a kind of startling way you need to lower them or add more compression to the whole track and readjust the level using the quiet-phrase check

Always do your best to check on both headphones and speakers and at loud medium and soft volumes. Headphones and loud listening levels tend to trick you into setting the vocal too loud, speakers and quiet listening levels tend to trick you into set the vocal too quiet.

Also in this case it would be best to set the reverb first then tweak the final volume.