Quite possible…you might be focusing on your chord changes, and getting sloppy with your strumming.
In the absence of pics or videos, I’d suggest the following:
Do the muted strums at higher and higher tempos. See if you start missing strings. Try to focus more on your strumming, and start hitting the strings again at that tempo. Or slow down just a bit, until you start hitting the strings properly.
At a much lower tempo (like 50% or less of your max in Step 1), try doing your chord changes - don’t worry if they are a little sloppy - you want to focus more on your strumming.
Alternate your focus between your fretting and strumming hands. Try to keep your strumming hand close to the strings. If it drifts away, bring it back. (It could be something else - changing your wrist angle, or your pick angle, etc) Go slow enough that you can see what’s going wrong.
If this doesn’t help…once again…video yourself (or at least take pics) , or demonstrate the problem to a more experienced guitarist. Doesn’t need to be an instructor…might be just a matter of going to your local guitar shop and demonstrating the problem to one of the salespeople. Most of them play, and can often be quite helpful.
Not sure if you have Justin’s app but if you do, he’s offering a free strumming course. Have to apply before the 5th. I did mine today as I’m only 3 weeks in but also lousy as strumming. I get panicky and start strumming too quickly, leaving the ‘song’ to sound like anything but……
As others have said, practice, patience and be kinder on yourself. I wish I could have told the 17yr old all this when I first attempted the guitar but nope, after a month and not being brilliant, I quit. Fast forward 4 decades and I’m still crap but I know I’ll eventually be less crap.
Hi Cate, @CateB
When you discover an error in your text, you can “Edit” it by pressing the pencil to the bottom left in your original post without this trick I would have had to make a thousand + extra post
I hope I helped you with this,
Greetings,Rogier