I really really disagree with the posters who are calling you abusive. Not because I think what you're doing is OK and you can just carry on as is, but because I think it's a hugely unhelpful label for you right now. You sound incredibly stressed and like you hate being Shout Mummy and you're asking on here for some help to change. I just think "abusive" is not going to be a remotely helpful thing for you to think about yourself and is just going to make you feel even more terrible without actually helping you to change.
Couple of things have jumped out at me from your posts:
It's great that your daughter has started at nursery. If she's only just started you won't be seeing the benefit yet, but give it a little time and it'll do you good to get a break from each other.
There are lots of medications you can take while breastfeeding. I really think you could do with going back to your GP and asking about it. You might choose not to in the end, but breastfeeding is not an insurmountable barrier.
Your home situation sounds really stressful. Your husband working a lot and not appreciating you. (I can't believe he got a takeaway for just him !!!) And you've got a young baby, you're breastfeeding, you're not sleeping well... I'm not surprised you're finding things hard. I often feel guilty about things like easy food etc, so one technique I use is to set a time limit on it. For the next month (or whatever) I'm just going to pick the easy way out every time, then on X date I'll pick myself up and have another go at doing things "properly". It means I can relax knowing it's not going to be forever and I have a fixed-time free pass to be "lazy".
If you can vocalise your escalating anger, you can be aware yourself of when you're about to tip over the edge. Our son doesn't tantrum in a typical angry way but he just dissolves into loud hysterical tears on a little puddle of desolation on the floor. Sometimes I can sympathise... sometimes it enrages me. To avoid shouting, I say, "I am going to go somewhere else now. When you have finished crying and can tell me using words, come and find me in the kitchen." Then I walk out and seethe somewhere else for a bit. If he follows me crying and I'm still that cross, I go somewhere else. Usually I do end up calming down and going back to him before he finishes crying and finds me, but I do need that breathing space somewhere away from the max-volume howling.
My favourite toddler book is How To Talk So Little Kids Will Listen. It's not really aimed at your problems, but you might enjoy it anyway. One thing it does have which is helpful is the "rewind" technique. You say: "Pause mummy! That wasn't very good. Let's try again. Rewind mummy! Ready? And...play mummy!" And then say/do the thing you wish you had. It's a very explicit way of having another go. I can't always stop myself shouting, but I can always apologise and have another go.