Anxiety ruined my day - loud voice in my head

I went to meet my sisters today for the first time in months, I'm a single mother and apart from the people I work with I don't meet with any other adults.

Today we went for a meal and me and my son got the train to see them in the town they live at, which was more convenient for them than us.

Generally my anxiety has got worse , I do checks around the house and check everything, windows are shut, sockets are off, doors locked, oven is off and taps are off .. everything aaaand to back that up I take photos and videos of it all to refer back to if I ever have a moment of doubt when leaving the house.

I went to a clothing store with my sisters and they are constantly by eachothers side , they kept making inside jokes and chatting away. They approached me together and told me they were going to go to another store and will have their phone on incase I'm done.

I go to try on a couple of clothes alone, take off my jeans and lay it on the stool In the changing room. As I get dressed and im ready to leave I hear them in the changing room area calling my name. This throws me off and I don't recall fully checking the floor that I got everything , I took a photo of like 90/95% off the floor but it didn't capture the very corner my jeans once laid.

Anywho.. I'm in the que and my thoughts get loud thinking " go check just go check you might have forgotten something " and I shrug it off cause my sisters are nearby waiting on me.

This plays on my mind for the rest of our time together, my sister even tried reassuring me that she opened the curtain and checked the floor for any clothes etc and said she wouldn't have seen something that I dropped and not told me. This wasn't enough I needed constant CONSTANT reassurance , so she did fact finding she said all I could drop from my Jean pockets was likely a receipt and nothing important. I just created these worst case scenarios in my head of yeah but what if and she said what If what ? And I said idk what if during the week when I had the jeans on I had wrote something important down ( which I generally don't remember doing ) stuffed it in my pocket without taking it out and then I'm fucked.

She tried to be tough with me and I nearly started to cry then she went for another approach, my son then met me again and I said I'm sorry I've got to check. I went back to the changing room and saw the stool had been moved riiiight to the other side of the room and in like fuck that's the corner I didn't check. I referred back to the photo I took before kicking myself I didn't remember checking and my mind goes blank. I know it's frustrating and sounds crazy but it still plays on my mind.

What do I do ?