Sometimes it better to sit down and explain how hard it is for you at time... My mother had the same view of not showing her kids she was struggling but that made for an example my brother took things for granted that she struggle to do but still provided for us.... And as a teen when I found out my mother was struggling not just providing and normal life situations but was dealing with a bit of depression... It hurt me and felt like she didn't trust me or think to lean on like she would tell me that I could tell her anything but she couldn't do the same...

I suggest starting with offering therapy if you're concerned. Make sure to give her her space with her therapist but that if she finds ANY potential red or yellow flags in the therapist to let you know. (Usually just things like how a therapy method or technique isn't working such as CBT not working if she needs DBT, etc)

I would recommend therapy for your kiddo as her depression might present different than yours and provide a safe space separate from parental bubble. As much as you will want to help if you force it or try to force her to listen she may push away. She needs a new space away from family and parents to confide in during her depression journey. However I would let her know that she's not alone and that you too struggle with depression. You can let her know how you struggled if she will listen but don't be disappointed if she pulls away. As a parent you will never want your children to struggle or go down your road but truth be told she's going down her own road. The best you can do as a parent that gets it is to love her, support her, and hand her or provide her with the tools but let her do it. There will be times she will ask for help and that is when you can step in but you also will have to learn how to step back again. She is building herself as a person and it's up to her to forge her road. Therepy is a great tool to start with.

Allow her to see you be human and to struggle, it's hard, but as I grew up with a mother with similar conditions as my own i know that if she shared that vulnerability with me then i would have truly known and understood when she told me she empathized with my struggles. Maybe look into some therapy, individually and together, some schools may have programs that offer it?:)

I would have rathered had my mom talk about her feelings and her go to therapy than figuring out just how messed up she is now. I've gotten some of my traits from her trauma because it was untreated (idk if yours is trauma related this is just an ex.) I just think you guys should start small, be open and honest.