Diapers are okay to use to help keep your bed dry and you comfortable. But you should go see a doctor to make sure nothing else more serious is happening as it's not normal for you to suddenly start wetting the bed again at 18.
Your doctor can also prescribe some bed wetting medication that will help control your bed wetting.
The depends protection with tabs plastic backed diapers will probably work good for your bed wetting protection.
You can also place a plastic bed sheet on your bed to protect your mattress from your urine.
Goodnites brand also sells bed mats that absorb urine and prevent your mattress from getting wet and ruined.