The seeds in the store change every 24hrs. The only thing you can do is keep using the three seeds you have and self pollinate each of them or if worst comes it it start a new game and download Borg's VST Borg's Non-Spoiler Virtual Seed Tray for Windows OR
[SPOILERS] Improved Virtual Seed Tray by Borg

These two program are for windows only, Borg does not have a MAC.

To use either of these programs you will need to download .net framework this is the link