Don’t feel any guilt whatsoever.
It’s your recovery. How you manage your recovery is your own business. If you want to smoke weed and recover then do so. There’s no hard rules about this regardless of what the 12 step programs say. The point is that your recovery should support your abstinence from the target substance.
Right now that’s methadone and likely dope as well.
For me, cannabis is just not dope, I can smoke weed til the cows come home, but it’ll never feel like heroin. That kind of clues me in to what I’m actually craving. Using weed is just a work around to the addiction problem for me. I’m not getting high on junk so there’s that. But I personally don’t like the way I feel on weed. I don’t like what it does to me. I know what I want when I smoke and it’s not the feeling of cannabis.
So, for me, smoking weed isn’t conducive to recovery.
But it very well may be for you.