Feeling like I am not doing good as a mother

Hello all! I have a set of 6 week old twin boys and a 16 month old toddler. I work in education so I am thankfully off for the summer and can spend time at home with my children while my firefighter husband works at his two station jobs (hes amazing and so devoted to our little family when he is at home as well). Besides taking my three online college classes and tending to the house, we try very hard to be involved with our children. My husband and i will play with our toddler on the floor, encourage walking, sing songs, try to talk through tantrums,etc and will do our best to talk with our little babies as well. It has been mostly me at home with the kids and i do my best to juggle them all, but when all three are crying for me at the same time, i feel overwhelmed and feel like i dont give as much attention to the kids as i should. For example, with my oldest, i always held him, i talked with him all the time, and always made sure his needs are met 24/7. With our newest sons, i still make sure their basic needs are met (feeding, diapers, etc.)and still play with my oldest on the floor, encourage our normal activities and whatnot, but i worry about our newborns. I feel bad that i hurry and rush to move to the next person who needs me or when i try to attempt to shower or eat before i get to one of them and i feel like they may not know they are loved enough. I barely get sleep and barely eat so i do my best to tend to everyone,but even that doesnt feel like it's enough. Im worried that my newborns won't develop as emotionally secure as my oldest did due to me not dedicating enough time to them like i should and have a lot of mom guilt. During the day after i lay our oldest down for his two naps, i attempt to eat and hold one of the twins (or both if i can) and talk with them for an hour or so, and at night, i cuddle them as much as possible,talk to them a a lot, and apologize to them while feeding. Im not sure if there's anything i am particularly asking,but i just want to make sure that my newborns feel loved and secure like my oldest. I feel like I'ma dedicated mother, but it's so hard right now.