1. Why shoot at F8 in natural light? F2.8 would have had the subject completely in focus at that distance. There was no benefit to going to F8. All it did was forced you to use higher ISO (which appears are noise since you under-exposed the images) and forced you to use a painfully slow shutter speed (way too slow for this) which resulted in some softness. Under-exposure + low shutter + high ISO showing up as a noisy soft image. Had you shot at F2.8, you could have used a faster shutter speed, and gotten a sharper image in general. Really though, for natural light, I would have pushed ISO to 1600, shutter to 1/60s at F2.8 based on your exposure, shooting in RAW. I would purposefully expose to the right, or gently over-expose without blowing highlights. This will help with noise control in post.
2. White balance. You're better off with a custom white balance in these settings.
Really though, if you want to do this more, use lighting. The light is bad, it's not friendly to your subject either. And it's so dark in these locations with bad tungsten light, it's hard for even a modern camera and lens to focus really nicely. I'm sure if you look at 100% on her eyelashes, they're fuzzy and indiscernible. In good light, you would have been able to count them with a sharp image with the equipment you're using. Considering you're using a $2.2k camera setup, I'd think a $50 flash would work wonders for you.
Pick up a Yongnuo TX-560 and a Yongnuo 560 IV (or III) [alt: just get a decent wired strobe with an umbrella mount, these can be $50~150 for good cheap ones], a Godox s-bracket [only for speedlite; not needed if you used a strobe], a boom capable light stand [not just any stand, get one with a boom arm, and get a decently heavy duty one, about $80 will do it], and a 31" or 47" umbrella (I would suggest a brolly box, umbrella style softbox) [these are great, $20 and $30, cheap and great]. If you use a speedlite, you can use a gel to match it to warmer ambient lights like that in the room. (Disclaimer: Don't buy anything though until you spend more time learning exposure and depth of field, there's no point in moving past what you have until you have a very firm understanding of those two things so that you can use your tool to get what you want from it and then you'll know what you actually need equipment wise to get the results you want)
Then you could have controlled ambient light and dimmed it down, and exposed your subject with soft light, and gotten tack sharp images.
If you want to stick to ambient/natural light, use window day light and warm it up. Don't just use a lamp. You'll get the results you did again, even with a 1DX.