I'm not sure what you mean about being a 4 and dropping to a 3, but these are my suggestions for your site:
Page titles: These are very important. On your homepage your page title is:
Mumszone - Home
Change this to something like:
Mumszone - parenting and pregnancy discussion forums, articles, chat rooms and competitions - Home
Then for example in the Site Articles section, instead of:
Mumszone - Site Articles
have:
Mumszone - parenting, pregnancy, baby and health issues articles and information - Site Articles
Page titles are used extensively by search engines and having descriptive titles will help your rankings no end!
Page Headings
On your homepage you have the heading "Welcome to Mumszone" - this is good, but in your code you should wrap this text with h1 tags. This tells the search engines that it is a heading and it is the main heading for your page, therefore the search engines will give more value to that text. Do the same on subsequent pages - so on the articles page you have the title "Mumszone Site Articles" - wrap this is h1 tags.
For some reason in your code you have 2 sets of title tags - I'd strongly recommend you remove the second set of tags.
Without being funny, a half decent Web designer should have done all this - and more - on your site in order to optimise it, but there you go!