Abandonment issues explains a lot!
It's really common for girls who grew up in care to have babies very young, as there is a craving for something that will love you unconditionally and babies can't abandon you. Attempting to seek out that family unit you never experienced, except so far all you've done is expose your children to an unstable home life.
It's great that your current boyfriend is sticking by and supporting you, but 2 years is absolutely nothing in the terms of a stable relationship. You need to be married, you need to be working more than the bare minimum and you need to experience being an adult with kids and not a kid with kids.
Also, I have 3 kids and had them all within 4 years and the practicalities of 3 is a lot. Most normal cars won't fit them in so if you or your partner drive you will need a bigger car, so you'll have that expense on top, you can't get in a taxi easily as you need a 7 seater which is more expensive and not ao readily available, you need a decent size 3 bed house at least as 2 kids will have to share and then when they get older you need a 4 bed as they don't want to share. Which is EXPENSIVE, especially renting. If you're in social housing the chances of a transfer to a 4 bed is minimal, in the housing association i work for the wait is around 10 years on average. You can't book one hotel room, you need 2 which doubles holiday costs. If you're on benefits there is a 2 child cap, babies are expensive!
It's not just cute baby snuggles and a "family" it's practicalities which affect everyone and cause a lot of stress.