So it took 5 hours for 462 satoshis. One question, I remember I had chosen 2.2 per byte. Can I somehow know how many bytes will my transaction be? So I can calculate the whole fee next time.
The whole fee isn't the relevant number when calculating how long it will take a transaction to confirm. The fee per vbyte is the number you want. Blocks can only contain so much data, and so miners will prioritize transactions with the higher fee per vbyte to maximize their profits. Paying 500 sats for a tiny transaction might confirm it very quickly, whereas 500 sats for a larger transaction will take longer.
If you are sending from Electrum again, once you have selected your inputs, outputs, and amount to send, it will automatically calculate the size of the transaction for you. If you click on "Tools", then "Preferences", then select "Edit fees manually", it will then display the size of your transaction next to the "Fee" input box. You should input the fee in sat/byte you wish to use depending on how full the mempool is and how urgent your transaction is, and Electrum will automatically work out the total fee you need to pay.