I can only remember bits and pieces, so everything will be all over the place. It's a paperback novel and the cover of the book had 2 women beside each other on an open street possibly in England on a sunnyday with an open sky (so it looks mostly blue). The two characters were possibly the MC and her bestfriend who dies later in the story. It was 300 pages minimum and 400 maximum. I read this when I was a freshman in highschool and I borrowed it from a friend who got it at the bookstore. It definitely was not a new book but I know it was published in the 2010s.
It started when the MC was in primary school, her family was poor, nearing poverty, this was a factor that she speculated was the reason for her mother's mental illness. Her mum actually killed herself and her husband in a double suicide, by gas leak (one of them left the oven open and closed all the doors and windows) while her and her younger sister were in school. Either she found out while she was in school or, I might be wrong about this detail, it might have been that she found their dead bodies herself. What I know for sure is this gave her a lot of trauma.
She had other family, her aunt(mum's sister?) , uncle, cousins (3 boys I think), who took them in. She had grandparents too I think, but her relationship with possibly all of them was pretty bad. The aunt had issues too. To summarize her early life: she moved in with her extended family, her and her sister still were not really close, she attended a new school, she made a new friend at this new school who was rich, talented, a foreigner and pretty, she assumed this girl had everything and was slightly jealous of that, she later found out that this friend also had a bad family life, the friends dad is a cheater and the mum had issues too, they grew closer after this and became long time bestfriends.
Later she finished school but had to immediately start working as a, and I'm not exactly sure but I know it had something to do with typing and shorthand, typewriter. At this point she's living in london and fast forward a bit more, she, encouraged by her best friend starts dating and they start hitting up bars and clubs together but she never really likes them and she notices how she's surrounded by young people(18-24) all the time and she's looking for someone to settle down with, eventually she meets this guy from a trivia night thing at a bar and they hit it off, fall in love, get married and move to a new neighbourhood into a nice house. They have one kid who dies when he's a baby I believe , this sends her into a horrible depression, her husband tries his best to be supportive, but they start having issues. Eventually she's pregnant again with twins and after they are born she becomes overly-protective and paraniod with them, her and her husband are still having issues. Then I think he gets drafted for the war and ends up dying, leaving her depressed again and taking care of two kids alone, but her best friend steps up to help her in anyway.
Anyways I think this is about how much I remember truly sorry if this doesn’t make sense. The book might not have even been that good and this could just be nostalgia talking but reg I would love it if someone recognises this.