need advice for my graphic design portfolio

While traditional carry portfolios might seem gone with the wind, you'll definitely need to organize either a printed portfolio or something you can display on a tablet if called to an interview. Hosting your portfolio on your own site is a great thing - but it should never replace a carry portfolio. In terms of a tablet device, a PDF on an iPad or similar device would be more than sufficient. A USB drive as a backup device might be handy. As always, the paper printed portfolio can't hurt.

In terms of content, if you're looking to work for a larger firm that handles more stiff corporate advertising and branding efforts - they I'd say pick your strongest pieces that demonstrate you have the value to produce their kind of work, and put those first. If you don't have anything that's falling into the fold of a traditional "corporate" theme, do some mock-ups or volunteer your efforts to some smaller businesses to gain experience. While the mock-ups might not be for a "real" business, they do demonstrate that you have the skills and eye to get the job done. Keep some organization to your portfolio and show you have some versatility to your style (if you do). Make sure to keep your pieces professional and only use what you're proud of.

Don't discredit your own work just because you feel it doesn't fit the model for a big-business identity. Keep your work and be proud of it. I know plenty of people who work at larger agencies and were hired based on some of the most untraditional styled work.

I don't think the Lorem Ipsum mock-ups are a good idea. I'd want to see real work so we could talk about the process of design choices and client interaction.

You said you've been at your current job for seven years. I assumed you were talking about a design-related job. Isn't there anything you can use from that experience?

If not, work on some self-promotional pieces.

While I am not a designer, I can advise you the following:

If you're dealing with corporates, chances are they won't even have the time to go searching online for your stuff. They're too busy and have a hundred other problems they have to deal with. Thus, carry some kind of printed portfolio with your best work. Present it to them, tell them how you want more challenging work and want to work more hours and provide benefit to the company.

Creating some mock-ups is, indeed, a great idea. Don't worry too much about the text - most managers won't really care. If you want, put something about how a great service increases shareholder value and provides synergy, enriching everyone's lives etc. in the brochure. Make it corporate looking and stylish. Everyone loves something that looks crisp, expensive and attractive.

On the other hand, don't forget to show more creative work and state that, if necessary, you can also work on more marketing/advertising/pr related stuff. Whatever.

Whatever you do, think in terms of a manager. What does he/she want to see? How much does he/she want to see? They're just people who want to see if you're a capable designer and can handle tasks they give you.

I think its stupid to use something polarizing like an iPad for your portfolio, all the people I work with make fun of the ipad and Im sure if anyone were to bring one to an interview it would be a negative. A lot of people think the ipad is really stupid so people that use one are taking a risk, not to mention it shows laziness since you didnt bother to get things printed.

Stick to a website and printed material.

There is an prior thread from February discussing using an ipad during interviews: https://forums.macrumors.com/threads/1093821/

as I mentioned in that thread, I interview a lot of designers over the course of the year... I do not meet with anyone until they have been vetted through their online portfolio. If they are "print-only" designers a PDF portfolio might be acceptable, but I do not encourage it. (Not having a balanced set of print and web/interaction design skills is limitation in this economy in my opinion -- the market is saturated with out of work print designers, but that is a topic for another thread)

I also have to voice a warning against "lorum-ipsum" mockups...

Consider that many of the people you will be interviewing with spend most of their day in the content business... marketing managers, ADs, CDs, content strategists...

Design is about visualizing and communicating content... how can this be done with no content?

This is a topic ironically I did a lecture about the other about design portfolios, I think the real question you need to answer is what it the dream job you want? Then you can find the places that will fit the model and you can apply around that. Are you print or digital because this will make a dramatic effect on how the portfolio should be displayed.

Print Portolios: need to be printed, digital will never replace the feel of a crisply displayed brochure.
Digital Portfolios: I would recommend then being accessible anywhere, so an iPad with a complementing web site would and in my experience works very well.

I know it sound silly but I would also only display the 9 best things you've done that does outline a broad range of skill/experience. I would also add a little comment about each of them that would fit into the SMART way of doing things.

e.g. In 2010 I created a brochure for selling sprockets, it was disturbuted to 10,000 people and Sprocket Inc's increase interest by 30%. (yes I know a very crude example).

I would also recommend using the social medias like LinkedIn and Behance, they are excellent tools for networking and finding work IMHO, I have landed many an interview via these networks.

I would also check out the following, though if you can look past the digital it does have some very good pointer that translate to print.
Creating a successful CV
10 Steps for the Perfect Portfolio