Panty pooping at the shopping centre

I'm an 18 year old girl and I was looking around a new shopping centre that had just opened near my flat. I'd been busting for a poo since the previous morning and it was just after 3 in afternoon when I really had to poo very badly and I had no idea where the toilets were. After a few minutes I spotted a sign for the toilets and I followed it but it was a long walk across the shopping centre and by the time I got there I was about to burst. I was so glad I'd made it without having an accident in my knickers knickers but my hope of relief was dashed when I realised the ladies weren't quite finished and I felt my bowels trying to push against my will. I clenched tightly while I thought about my options. I thought about using the men's toilets but I felt embarrassed to do that so I decided look for some other toilets. That was a decision I came to regret because these were the only toilets in the shopping centre and I'd just walked around the whole place for nothing. By now I was beyond just being desperate for a poo. I had a biological need to empty my bowels and I couldn't hold it any longer. I felt my bowels pushing again and there was nothing I could do to stop my poo from coming out into my knickers. I was so embarrassed but the relief of it was so good I didn't really care. I just pushed and over the next 5 minutes I completely filled my knickers and I even wet myself. I felt so much better when I finished but it was very embarrassing having to walk home with my jeans and knickers full of poo and soaked in pee.