The matches in Raid are determined by cups/trophies. If you are within 300 cups of your opponent, you can draw them in Raid.
The exception is in Revenges, where I believe cups goes over 300 to make the matches.
Everyone goes through a rough patch (sometimes a long, drawn out, interminable patch!) with Raid. Don’t let it bother you. Fight who you can; if you need ham, don’t reroll.
I actually ignored Raid for nearly two months once. No worries.
P.S. DONT upgrade your watchtower if you are trying to avoid Raid fights; sometimes that full ham/iron draws greedy opponents. If you don’t care about trophies, raise the Watchtower at will…it will give YOU free ham/iron every time you empty it.