I work in a very corporate environment I'm 27 overweight and I always feel scruffy and out of place. My hair is all over the place and I manage to ladder my tights on a near-daily basis. I'm chubby with enormous boobs and my jackets always sit it in a weird way. I never manage to get the same level of mascara on both eyes.
I don't think people notice as much as you think they do.
I'm in the process of leaving my job for a new better role in the same field. Cue massive pre-interview anxiety about what to wear, about how my hands sweat when I'm nervous and how I can hide that when I have to do handshakes etc etc etc.
We had my leaving do last week and among other things, I got a voucher for a monthly manicure for a year from a parallel team. I was mortified and must have gone bright red, I thought it was a suggestion that I do my nails better or look after my hands more. The guy who gave it to me then looked embarrassed at my embarrassment and said "but you always have the most perfect nails, so we thought you'd enjoy manicures, but if that's not your preferred salon I'm sure we can exchange it"
And it's true, I do try and make sure my nails look alright, I don't really have manicures normally though....
As previous posters have said, you might have more of an anxiety than an appearance problem and honestly, as long as you don't go too wild with colours, short skirts or low cut dresses, I'm sure people don't even notice.
Again as PPs have said, you have your job because of your brain. And as far as I'm aware ( and I say this as an overweight frumpy scruffy person) being scruffy doesn't affect the way you do your job. It can even to the contrary show that you're more than an Instagram obsessed millennial.
However I dress, I feel like I'm dressed like shit, but hey, I get shit done. And I'd rather it that way round.
Things can and will get better.
If you're really self-conscious, start with little things,
- Clean glasses if you wear them
-Extra tights in your bag in case you ladder them
-Polished shoes
-Clean nails
-Neat eyebrows
Then try and adopt a fuck it attitude - it helps
best of luck