You are probably being overly self critical.  If you don't have a singe project worth putting into your portfolio you most likely would not have made it as far as you have.

Your best course of action is probably just to tweak the work you have.  All those changes you wish you could have made but lacked time for you can now implement.  Add sketches or diagrams to help show your thought process.

If you absolutely don't have work worth showing (again highly unlikely) you could consider design competitions.

Yes to the above comments, go back and re-do previous projects. That could mean tweaking or it may be re-doing entirely. If you have the premise for the project re-do it until you get something you like. That's a start...your question could receive lots of in-depth answers...

Even without reworking anything you can probably find a few good images from most of your projects. They might not be from the final presentation, or the images that the studio professor liked best. Keep in mind that you have the advantage now of being able to "spin" the work any way you want - you don't have to tell your portfolio's audience what the real program was for the studio project, or show all of the work from the project - you get to tell the story in any way you like now, and that best suits the work that you do have.

You may actually have an advantage, in feeling like you don't have enough good work.  The biggest problem with most recent grads' portfolios is that they're much too long and unfocused.  If you only have 6 good images and you make that your whole portfolio, you'll get points for restraint and focus, and the discussions in your interviews will probably be less scattered and hurried than they are when somebody comes in with a 30-page portfolio of cluttered pages filled with every preliminary site diagram from every studio, plus 4 pages of life drawing, some photography, and the vase they made in high school clay club.

If you don’t have work worth showing you probably don’t even need a portfolio ;)

Don't waste time reworking anything until you discover you're unable to move forwards with what you already have. You will, in rapid fashion, have more than enough new work to eliminate your school work from your portfolio altogether if that's what you want.

It will also give you the excellent skill of talking about projects you're less than thrilled about in a way that makes you sound like a desirable  future member of the team. Considering you'll likely be working for someone else and won't always see eye-to-eye with them, it's a skill worth having.

If i learned anything important in architecture school, it's figuring out how to make things work. Sometimes the projects that I hated the most, were the easiest/clearest to explain/get the point across. Just take a step back and figure out the issue and then find a way to solve it for a quick presentation of your work. 

I reworked one project in my undergraduate portfolio. It didn’t create an overwhelming amount of work but still set the tone I was trying to convey for the first project in my portfolio. After that, I graphically aligned my other projects to read more like my first project so my portfolio looks more cohesive. Try that? Good luck

You could always re-work the project and graphics to read cohesively in your portfolio. Nothing wrong with that. Just because the project has been "graded" doesn't mean you can't refine it afterwards for your own use and portfolio.

Thank you all for your comments 

I feel the same, I actually don’t know how I passed architecture school with a 3.3 gpa. My projects are awful and I’m now thinking of going portfolio-less to interviews, etc... what I would want to do is redo some renderings and plan if you’re really unsatisfied but for the most part, many firms, (unless you’re working for a starchitect) won’t care about the content of you portfolio as much as they will about attitude. 

Unlike an academic portfolio most employers do not want to see lengthy projects and the accompanying narratives / post rationalisation. They've seen it all before, and mostly it will be irrelevant in practice. 

Be selective and choose elements from your work that not only showcase your ability, but illustrates your likes, and an insight into you as a designer. Ultimately, this will land you a job you are more suited for. 

You can rework the projects you think are the best ones to the highest quality possible. Assuming you are a fresh grad, 3 projects are enough. Polish everything, make a neat layout, pick the best image from each project and present it in large scale. Add everything that you don't have, sketches, models. 

Just motivate yourself and get to work really. Once you're done you will be proud of what you have accomplished.