A hook? Sounds fishy to me!

It's July and I've received my 5th rejection! Looking on the positive side, I was told that the main problem was that the 'hook' didn't grab them in the first 3 chapters I'd sent in. What's positive about that I hear you ask? Well, they hadn't laughed at my efforts or sent it back with a big red line through it. (Hang-ups from school days!)
Having mulled their comment over, I knew that they were right. I was too busy introducing characters and setting up the 'hook' in the first 3 chapters and it needed a re-jig. If only it was that easy! I imagined I could cut and paste a few paragraphs and be ready to send it off again to another carefully sought out agent. Then it slowly dawned on me that in order to get the reader gripped and wanting to read on, the 'hook' had to appear in the first few pages. This changed the opening scene, characters, time and month!! What made this even more difficult to do, was that I'd won a first chapter competition with firstwriters.com - and if I changed it, the winning chapter wouldn't be first any more! Do you see my dilemma?
I decided that I should listen to the professional agent, and morphed the 'hook' into my first chapter. I had to change lots of conversations and thoughts which my characters had had, in several chapters, but it seems to have worked. I can see now that it has improved my book and was worth the late nights, extra grey hairs and increased levels of sugar consumption. These problems are easily remedied by earlier nights, hair dye and going on a diet!!
Now I'm trying to design a book cover for my novel. I know that agents hate this, but I'm not doing it for an agent. I want to upload my work onto Harper Collins authonomy website and they require a front cover for that. I visited Harper Collins in February for a workshop and listened to what they had to say about the new site. It's an excellent idea which introduces new authors and their work to each other. The top five novels are looked at by HP agents, which is a great opportunity for the writers.
So I happily plod on. The key word being, happily. I love writing for the thrill of using my imagination to do anything I want with my characters. I'm on my second novel and wake up each morning wondering what calamities, adventures or love interests my characters are going to meet that day. And I'm in control!