Need more Butterfly Food!!!

This year I have been in short supply of butterfly weed, which is the only plant that Monarchs will eat and lay their eggs on.  I have had so many butterflies this year that I just can't seem to keep the plants around long enough for all the caterpillars.  I have a good amount of butterfly weed that usually grows in my garden. I will only grow it for the Monarch butterflies.  I don't care what it looks like after the caterpillars get finished with it.  And honestly, it looks pretty bad.  Nothing but stems and no leaves. Last year I didn't have hardly any butterflies.  I probably had 4 or 5 the entire year.  I am not sure if the number of butterflies was lowered because of the drought that we had here in Texas but I think it is a large part of it.  Maybe there was not enough nectar plants for them. Also,  I don't think there was enough wild butterfly weed out there for them to eat or lay eggs.
This year we have had a great spring with lots of rain and with that came lots of butterflies.  My boys and I usually help raise the caterpillars inside our house in a terrarium because the red wasp will eat as many caterpillars as they can sink their teeth into.  But we have had so many caterpillars that I have kept most of them outside on the host plants.  I also have not seen any red wasps this year.  Not sure why?
Six days ago I ran out of food for all the caterpillars.  And I still had about 18 caterpillars that were still growing.  So my oldest son and I went down to our favorite nursery, Enchanted Gardens in Richmond. We bought 4 more good sized butterfly weed plants.  Brought them home and moved the remaining caterpillars onto the new plants.  It only took them 3 days to devour them and we were out of food again.  This time my youngest son and I went back to Enchanted Gardens and bought one more plant.  We only had 7 caterpillars left to get to cocoon stage. Now we have 5 caterpillars left and one is getting ready to cocoon.  We have only half of the last plant that we bought left.  Two of those remaining caterpillars will stop eating within the next day or two. So I sit here and wonder if I will have enough food for the last few caterpillars.  The good news is that all of the original plants that I have in the flower beds are all starting to leaf out.  So I do have hope for the remaining few caterpillars.  Keeping my fingers crossed.  I don't want to keep going to the store to buy more butterfly weed because I tend to find new plants that I want to add to my garden.  There is so much to choose from, I can never have enough plants.