Failure as a parent? Any advice for a young struggling mom?

I feel like a failure as a parent I wish kids came with instructions because I feel like I am screwing up left and right. Heres why. So my 2 going on 3 year old daughter still takes a paci at night and for naptime. She still uses a sippy cup at home and in car due to trowing or dropping her drinks. She also isnt potty trained because she refuses. On top of this due to her being around my spoiled 6 year old sister she doesnt share well and back talks adult. Im currently living with my parents who i moved in with two weeks before having my daughter, but my boyfriend and I are looking for our own place and trying to be moved out before the end of summer. We both have steady decent paying jobs. My mother is well for lack of a better term a pos I basically raised my siblings growing up, and her husband is an asshole who basically just yells at kids left and right. And ive had my daughter in this environment for two years. I feel like i failed my daughter because she is so far behind in so many ways and has been living with these people, but in other ways she is so smart she knows her colors and some of her letters and has great manners in public. She is typically a sweet happy child until she gets around my parents or sister then she wont listen and destroys things. I am due to be induced on Wednesday with my faternal twin boys. Im so scared im screwing these kids up I have no idea what I am doing and I'm so afraid to turn out like my mother and have my kids resent me for their childhood. How do you be a good parent when you've never had one? Sorry for the long post if you read all that please be kind in the comments I feel shitty enough as is.