I’m in the same boat babe I have one pair of flared leggings I wear every single day lmao and the only income I receive is child benefit but that’s for my son. I have a couple of times used Klarna for things like SHEIN or boohoo and forgotten a payment or not had the money to pay the payment. I too gained so so much weight and hate myself so I totally understand the need for new clothes & I just binned all my clothes too😫
Rather than getting into debt, reach out to charities or free Facebook groups. There are always people willing and able to pass on their unneeded clothes. Debts can escalate quickly and there's absolutely no shame in asking for help. Hopefully before long, you'll be on the other side of things.
Vinted!!! You can get clothes for as cheap as a pound. I echo the above comments about reaching out for support but don’t fall into the trap of these buy now and pay later especially for things you can get significantly cheaper on places like vinted. I’ve bought stuff with tags on for a fraction of the price.
You can also sell stuff you don't want on Vinted too
If you are struggling financially you need to ask for help: universal credit, council, etc. Your baby's dad needs to help, if he doesn't there are support channels that will help you to get this. I don't know much about how to ask for help but I'm sure there is a lot of information on Google. Good luck