Hi,
I'm so excited cos I had a go at making the ones I posted a link to, using the blog by Katrina & the original link she posts (shows how to draft your pattern & sew it step by step).
I'm no great sewer, but managed fairly well (I wouldn't be putting them on show, but they'll do the job!)
Thought I'd share what I think has worked...

I made the medium pattern first for small 15 mo dd (she's around 9 kg, so tiny). Cos fleece isn't stretchy I didn't do the waistband, but added 1 inch for a turnover for elastic instead. The rise was still pretty short, and overall the trousers looked pretty small. We use a really bulky nappy that I want the flongies for (tots bots fluffies), mostly at bedtime.

So then I undid the elastic turnover & made the waistband after all. Not sure if it will stretch very well, but the pants are a better size now. The pattern is quite a nice cut. Would also make nice ordinary trackies I think. These prob won't fit dd, but will fit my friends 5 mo (I think)

Then I had a go at the 'large' size, but altered the pattern.

I added approx 2 inches (generous 2 inches) at the top for the elastic turnover and a generous inch down the width of the cut. I did that by not cutting off the paper next to the red line, just overlapping the extra margin there (if you print off the pattern you'll see what I mean, if not & you want to know, ask & I'll try to explain better).

These worked out a much better size I think.

For both pants, I then made another layer (this is another reason I wanted them generous size) for absorption.

I did this by cutting out some 'shorts' using the pattern (used just the actual pattern but not the inseam/leg length - you'll see what I mean if you look at it). Then I attached this near the waist. In the waistband seam for the small pair, near the elastic seam for the large pair.

I even got the lettuce edging to work.

I'm no great sewer, but I have managed to do all this in around 2-3 hours. Next time it'll be quicker cos my pattern will be all sorted

Hope this is helpful!