You've been given very good info, and as they say don't take it to heart when they complain and mess you about or dump you.
It's taken guts to do what you've done so far, and I would say you will be a success because of your attitude.
Everyone on here, repeat everyone on here says they priced too cheaply to start. So take the advice you've been given.(I know you have been doing, i'm just reiterating that people are saying)
Just read your last post, everyone thinks they live in the worst town; You don't, look at a £1 a window. Don't make a life of misery for yourself, if you are going to do this, do it well with good prices.