OK, I'm seeing plywood, lino (linoleum?), and poly varnish (polyurethane?). Anything else?
Plywood--if it's the least expensive construction grade has glues that can outgas for quite awhile.
Linoleum-- "The main ingredient of genuine linoleum is linseed oil. (In Latin, linum is the word for linseed, which comes from the flax plant, and oleum means oil.). The oil is boiled, mixed with melted resins, and combined with powdered cork, wood flour, resins, ground limestone and other natural materials. Mineral pigments provide the color." from
Linoleum Frequently Asked Questions
Purportedly linseed oil is nontoxic. However, if the material you used is not genuine linoleum, you might have some toxic materials. Or some of the other materials in linoleum may be toxic.
The varnish--is it completely dry to the touch? If not, it most certainly is still outgassing. However, it can still be outgassing even if it feels dry to the touch.
Or it maybe some other components you used in the build? Can you name all the components you used in the build using full names?
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