Now that you are into the Guest Race chapters, there will be a couple of goods you produce for each chapter that have a limit on how much you can hold in your Portal building. The best thing to do is to level your Portal to the max of 4 as soon as you can, so that you can hold more of those limited goods. On the plus side, any of those Portal Profits you may have collected by now are used specifically for these limited goods, so you can get more without having to produce them.