my honest advise is maybe not what you want to hear, but could be simply expressed as: "pick another project"...
it's going to be hard to get real academic content into an e-commerce site.
Your project cannot simply be, here's five bad sites and here is my good one!
and when you say E-Commerce site it sounds like you want to build a shop...
Your tutors advise is don't build a site, build a tool that anyone could use in order to create an e-commerce site.
(e.g build a CMS system with a store/shopping cart builder)
I'm guessing that you want to build an e-commerce site because you have a particular passion, (lets say you want to go into building custom PC's and it's a great excuse to use your final year basically researching and launching your business. -that's where your passion is, and probably not in making website building software??
Your final year project takes loads of time. you need some dedication to stick with it.
if you keep on down this route you need to end up with a concise statement of what you're doing. (building a e-commerce framework)
you then need to evaluate existing products and show their weaknesses. (e.g lacks plugins, lacks currency converters, no ability to use templates for custom layout. no ability to create custom products from raw materials lists, limited stock tracking etc)
You need to evaluate technologies, why PHP? why not perl, or ruby, or ASP, or ASPX, why not a binary executable C file.
You need to evaluate database choices. both in terms of cost and scalability efficiency etc!
Long story short you can't just build a website for a final year project.
Other choices might inlude,
Writing some forum software. - I.e find a gap in the market and fill it (likely impossible to do in a year!)
Write some POS (Point of Sale) software for small shops. - most people have an android/iphone etc that can run bar code scanning software. - can you make a bit of software for small shop keepers (e.g. so they can stock take by scanning a product and entering a QTY with their phone, that'll update a master database.
when they sell something they scan a barcode with the mobile device, and this updates a running total on the screen, can you print this wireless (many wireless printers can accept jobs directly from phones).
can you make the app (either on the phone or on a server that holds the database send reminders to buy more stock, create catalogues for online shops. or do accounts?) - so far as I know this does not exist.
-again you need to evaluate platform choices (almost certainly android since you probably can't get your app into the appstore).
you need to evaluate code choices,
database choices etc.
When your tutor said look at frameworks, they meant that building a website as a final year project is too simple. (and a look in the evaluate my website section here that shows 12 year olds writing PHP sites would suggest this is true"!) you need a "meaty" project as a final year project. taking something ridiculously simple will guarantee a low mark. (that said ridiculously complicated will just ensure that you don't finish either!)