Cut roller blinds too short

[applesauce1]

I'm putting black out blinds up in baby's nursery. I followed the guide and cut them down to fit but they ended up being a few mm too long. I cut it down again and now it's too short! I'm so cross with myself as I've spent 3 hours on this blind already.

Is there a way to fix what I've done? Do I need to buy a new blind and start again? Baby is due in December so I have time to start again if necessary.

Trying to be kind to myself but I'm feeling quite cross with myself right now...

How much too short? Do you need to stitch a baton in to place? If you could avoid using a baton and stitch some heavy trimming to the bottom edge that might work?

And... I feel your pain! This is the kind of thing I do All.The.Time!

Add some trim, or add a contrast strip part the way up to lengthen it again.

Stupid question, is it now too narrow horizontally, or too short vertically?

If the former I don't think there's much you can do. If the latter you could add a bit if you can source blackout style fabric, or possibly move the blinds fixings down and put something more permanent over the very top of the window. It should be blocked from your sightline by the roller.

IME blackout blinds never fit quite perfectly, you always get some chinks of light through the edges. Secret option C is just live with it but add blackout curtains too. They'll have their own gaps round the edges, but belt and braces approach leaves it pretty dark.