Two under two

I have 3 children - 5, 18m & 6m. I struggle with anxiety and depression and I want to know how other mums cope with 2 under 2! At the moment it's just a constant cycle of screaming, feeding, changing butts and it's a challenge to get anywhere. The eldest two fight and there is rarely any nice play. The middle child is constantly on me - even when feeding the baby. It's just so draining. The eldest two also go to Childcare 2 times a week, my husband works long hours and I do not have any family help I can rely on and the rest live interstate. I love my kids and we have happy times together but seriously how do people do it? When actually does it become fun?