Step parenting advice please

Ashlee • My family ❤️my kids👬👭my boyfriend 💖my baby on the way🤰🏻🌈❤️🙏🏻🙂

So I'm having a hard time trying to parent/step parent the best I can I have been with my boyfriend for 2 almost 3 years he has 2 sons with his ex that unfortunately passed away when his boys were still very very young I have my 2 daughters my oldest is 7 and youngest is 2 almost 3 I met my boyfriend when I was 10 weeks pregnant with my youngest so he is the only father she will know I do my very best to treat all 4 kids the same. And I am now 12 weeks pregnant with mine and my boyfriends first baby together I'm so excited and happy. I have been finding hard to step parent my step sons there at the tender age of 12 and 11 and have all the attitude and back talk and crazy moods to match the age. I know they suffer from emotional problems and I work extra hard to be understanding loving and caring but nothing seems to work I know they can be stressful for my boyfriend especially when there are disagreements between me and the boys. I've tried talking to them family meetings talking to them one on one as well as my own children I'm very into communication with my family and trying to open those doors for my kids as well but it gets harder and harder my boyfriends youngest son will have explosive emotional breakdowns from time to time and it's only when I'm watching them during the day it's scary and very stressful for me because as a step parent there are lines we can't cross as we can with our own kids. I've talked to my boyfriend about it I've cried begging for help I don't want to leave my boyfriend I love him and all the kids so much I'm just at a loss and now being pregnant I'm trying so hard to fix everything before the baby arrives I strive for peace and happiness in my home but I just don't know what else I can do

I just want to be the best mom the best girlfriend and person I can honestly be. Positive comments are welcomed any negative comments please just keep to yourself thank you