Hello Christie,
Thanks for sharing your concern, as discussed on live chat. there is no issue with size or creating any other product option in sellacious, hundreds of other website owners are using product attributes and creating their products in different sizes, colors and specifications every day, its just a learning curve. Kindly follow the documentation or contact us in case you find any issue. If you go for a premium you can use one to one live session of training as well.
-Abhishek
Team sellacious