I dont know what to do

This is really long. I never intended for it to be but its just massive rant. Thank you if you read it all.

I'm a mum of 2. Im 20 and I have a 19 month old and a 4 week old. I have a fiance whos 21 but I'm basically a single parent. All he does is work. He took 2 weeks off work after our second daughter was born, so hes been back 2 weeks now and hes had 1 day off and he slept all day so it doesnt really count. Hes self employed so doesnt have to work every day and we dont desperately need the extra money. I was worried about having 2 kids and having to do it myself 5 days a week because he usually has every weekend off apart from the odd one every now and again if hes near a deadline. It was working fine for us before but now since hes gone back to work hes never here. He starts at 7am so hes gone before our babies wake up then come home at 6pm so hes sees our oldest for 1 hour before it's her bedtime and he hardly spends time with our second he just sits on his phone. Anyway obviously everything has doubled since our daughter joined us; washing, demand for me, mess, etc and theres just not enough time in the day. I'm getting 2-3 hours of broken sleep a night if I'm lucky and hes not done one night feed since weve been home from hospital. My daughter doesnt understand when I cant do what she wants straight away if I'm busy with the baby I try to get her involved as much as possible but it's a lot for her so she just cries until I can help her. The baby isn't the best sleeper she just wants to be on me all the time. She will sleep by herself for an hour at most if I'm lucky. And inbetween this I've still got to make dinner and do all chores. I know I'm a stay at home mum but this is hard and he doesnt understand. I've asked him when he will take a day off to spend with us he said he doesnt know. I cant go out much on my own with them as I've not quite mastered sorting them both out in public on my own yet. Weve been on short walks to the shop or the park but that's it. And now it's the school holidays everywhere is packed for 6 weeks so I'm not so confident taking them out when I know its busy everywhere and my daughter will want to run off a play and I've still got the baby to watch. So I suggested it would be nice if we could all go out together so we could manage them together one of us play with her then swap or something similar. But he said he doesnt know. Its like he would rather work than be here with us. I feel like the worse mum ever. My toddler is so bored shes started becoming defiant and not listening and doing what she wants and when I'm halfway through feeding the baby and shes halfway through squirting a tube of cream everywhere or climbing on the table, like what am I meant to do in those moments. I know it will all be fine eventually but I just dont have the time to sit and play with her like I used to or take her out all day and go on little adventures. We cant even go in the garden because he got a puppy 2 weeks before my due date so the garden is full of dog poo and overgrown grass and I dont have the time to sort it out and I also said when he got the poor thing that she would never be my responsibility I feed her when hes at work but that's it nothing else. I cant deal with a puppy as well as two babies. So I feel like if I ever need a break or help then I have to ask family because I feel like I cant ask him because he would rather work all the time. But I can't rely on family these kids are our responsibility not theirs. I cant even have a shower and leave them with him downstairs without him pestering me every 10 mins asking how long I'm going to be. I just dont know what to do or how to make him spend more time at home if he obviously doesnt want to. I'm struggling to keep myself sane looking after them both 24/7 for the last 2 weeks it's been really hard I get little to no time to myself by myself to sit in peace or just to do something I want to do I've always got a kid stuck to me. Trust me I love them but if I could have someone else look after them so I could take a long bath and have a full night's sleep I would happily let them take them but no one will and it's bout fair for me to expect anyone to apart from my fiance but he wont. He doesn't hear them cry in the night he sleeps straight through so it's not like I'd even be able to sleep through and relax properly because I can't trust him to hear them. Im just stuck.