I sent too small of a transaction fee, is my bitcoin lost forever?

I sent too small of a transaction fee, is my bitcoin lost forever?

If the transaction never gets confirmed into a block - the mempool expiry of all nodes will drop it eventually and you will be able to spend your funds again - typically it takes about 3 days or so for this to happen. If using an [SPV] wallet such as Electrum or Multibit, if after three days the wallet does not see the coin to spend, you need to reindex your wallet's block headers. After reindexing, your wallet will see that the coin was never confirmed and thus the balance will be spendable again.

NOTE: From Bitcoin 0.14 “transaction reappearance” happens after 2 weeks.