I understand the predicament you are in. In my opinion it is a privilege to have friends and family for support during special events but that support should not be expected in the form of gifts.
Gifts is a generous thoughtful way to be helpful and kind but it shouldn't be a requirement!
I will be honest I have always given gifts but it's because I am able to or that I can but I feel it shouldn't be a must. For instance I am not a fan of gift registry. I feel it's rude to imply where I am to shop for someone, how much I am to spend on them, and that I have to bring a gift.
When I invite guests to any of my functions I let them know that they are important and not gifts.
You know... they might not care if you can't bring gifts they just might want YOU there and not what you can provide them. Either way I do hope it works out for you.
Good Luck