Although your bitcoin came from a legacy address, it looks like Mycelium sent your change to a nested segwit address. When entering your seed phrase in to Electrum, check the box under "Options" entitled "BIP39 seed", and on the next screen click on the middle option entitled "p2sh-segwit (p2wpkh-p2sh)". This should change the bottom box to m/49'/0'/0'. Click next, and hopefully you should see your change address show up in that wallet.

As hosseinimr93 says though, a CPFP will at most boost your fee to 23 sats/vbyte, which would currently still put you around 19 MB from the tip which is unlikely to confirm until the mempool empties a little at the weekend.