12 vs. 24 words seed

You are fine to use 12 word seed, it is safe enough

While using Trezor Wallet, Trezor Model T creates a wallet with 12-seed words and Trezor One generates a 24-word seed. Both models are compatible with public standards and it is possible to recover your wallet with 12, 18 or 24-word seed on both devices. In terms of security 12-word recovery seed is safe enough.

12-word seeds provide 128 bits of security, 24-word seeds provide 256 bits of security.

While Bitcoin utilizes 256-bit private keys, the security of the elliptic curve is around half of the used bits, so 128 bits for the secp256k1 curve that is being used.

Source: Recovery seed - Trezor Wiki