The size kind of depends on what all you would like to carry in the bag (but still keeping it fairly small).
I have made a smaller size as well & it turned out fine. I will try to give instructions but I'm really not very good at explaining things! :)
I made this one from:
2 pieces of fabric - 7"x10" **
1 piece vinyl - 6"x7"
1 strip coordinating fabric 4"x7"
** I trimmed the corners off of the two 7x10 pieces to create a little variety in the flap. You could also round the edges.
Fold 4x7 piece in half lengthwise and press (wrong side together), then fold raw edges in towards fold and press again.
Then slip the 7" side of the vinyl into the fold and stitch in place.
[I do this to have a more secure base for attaching velcro or snap)
Now attach you velcro/snap in center of that fabric strip.
Place the pieces of fabic you would like to show through the vinyl right side up with the vinyl piece in position on top of it.
Make sure you place the vinyl right side out; velcro showing. Make sure bottom edges are aligned!
Next place the other 7x10 piece (will be the outside of bag) right side down on top of the fabric with the vinyl.
Pin in place if you choose.
Stitch around the edge with a generous 1/4" seam. Leaving a few inches for turning. I leave my turning gap at the top.
Turn right side out and stitch opening closed. Attach velcro or snap to top flap.
Fill with items baby/toddler might need (i.e. thermometer, neosporin, antibacterial wipes, bandaids....endless possibilities)
Smaller version (first attempt)