Baguettes are not bursting at the seams

Could be a sign of under - could be a sign of over - could be a lot of things. Keep things the same and try one or the other. See what happens and go from there. Enjoy!

When scores open vigorously it's a sign that the loaf had a lot of oomph - the power to rise strongly and force the dough to expand a lot. Here are some common things that could reduce the oomph -

1. The dough has already risen about as much as it can, so it doesn't have much left to give during baking.  The total volume can be good, but most of it was achieved before the bake started.  Shortening the proof or even the bulk fermentation will help with this, since it will leave more rising power in reserve.

2. Everything was was otherwise OK, but the yeast ran out of food before expansion was complete.  A very pale crust could indicate this.  I'm never sure just how much of the final rise during baking is caused by yeast, but some of it is. (Other sources of rising are CO2 coming out of solution as the dough heats up, and water in the dough evaporating and expanding, making the dough rise). It might be that your flour could benefit by the addition of a little malted barley or some sugar (depending on the flour, of course) to provide more yeast food.  If this happens it also suggests shortening the fermentation periods so as not to use up as much of the yeast food.

If you refrigerate your loaves for some time before baking (hours, at least), the dough will be able to dissolve more CO2, and this should give more oomph during baking if you bake them right from the refrigerator.  If you retard the loaves this way, make sure to put them into the refrigerator roughly an hour before they would otherwise be fully proofed, since they will continue to ferment as they cool down.

3. The steaming of the oven wasn't effective enough so the crust has gotten stiff before it got a chance to expand to expand fully. Try to generate more steam if you can.  I'm assuming you are using a baking stone or steel.  If not, getting one should be your first move.  The stone or steel keeps pumping heat into the loaf while the steam has cooled down the crust and oven air temperature.  This heat keeps the expansion going while the cooler crust takes a longer time to expand.  This usually leads to better expansion of the scores.

It will also probably help if you keep the scoring blade closer to horizontal, so as to create an undercut lip.  The first of the pictures looks like you may already be doing this.