I like chagzuki's last suggestion. There may also be other parts that can be replaced by lighter versions. I don't know if this will get you the weight you want to be at, but it might put off the sale of your Brommie for a few more years.

That said, I have a Bike Friday Tikit, and I used to use it all the time for grocery shopping. Just put a pannier on your front rack, and you're good to go. It does take a little getting used to, but once you've got it, it works decently. Unfortunately, you always have to balance it... so your arm will get a workout if you have to roll it around for an extended period of time. My goal while rolling it was to get in and out as quickly as I could so it didn't bother me much. As others have noted, you have a lot of gearing options on the Tikit and semi-custom sizing (Small, Medium, Large).