You mention your looks being what's getting you down but that's probably a symptom of the other problems in your life.
I definitely 'lost myself' in my 30s. My job was made redundant and I ended up redeployed into a job I hated. I didn't really appreciate it until later, but a lot of what happened then knocked my confidence. I then had kids and that really knocked me. I had PND and anxiety. I then got redeployed again while I was pregnant with DS2. I did a job that wss perfect for childcare, but terrible for me. I felt trapped and I remember feeling like I didn't matter anymore, I had to do what suited the kids. I worked evenings and had two kids under 5 at home all day so NEVER had any time by myself (I'm someone who likes my time alone).
I started finding my way back when DS2 was 3YO and I went back full time working days. I got evenings to spend on myself. It has snow balled since then. I still hated my job though!
Interestingly, it has been lockdown that helped me find myself again. I got off rhe hamster wheel of life, did a lot of navel gazing and made some big changes. I found a new job which I am happy in. That has made a lot of things in my life better too (because I WFH and I'm less stressed mainly)
My weight got upto the highest it's ever been in this time, mainly because I had no time to exercise or cook healthy meals. But I also had no time or energy to deal with my feelings so I binge ate as a way of dealing with them. Now I am in a better place emotionally, I am working on my binge eating.
Something I have also 'worked on' (hate that expression) is that it's OK to look different to how I did when I was 30. I'm 41 now. I've been through a lot, I am a different person because of my experiences. I do still do my make up, wear nice clothes etc. I'm eating better and exercising. I've accepted I'm different now though.
Take it one step at a time. I found things snowballed, one little thing boosted my confidence and made other things easier until I started doing loads of things together. Life gets easier as the kids get older too. Don't put too much pressure on yourself if you have a young baby or toddler. It will come, but it does take time.