Bread in the Form of Squashed Rolls

I've always had a floppy experience working with yeast. In Food Tech in Year 9, as a fun end-of-the-year project, we all made some bread. SC and I wanted to make chocolate cheese bread but we weren't allowed to because the combination was apparently ridiculous. We proofed our dough (chocolate and pistachio, a much more conservative combination) in the bottom of the oven, with yeast from the same packet as that of the other groups.

After baking, our asterisk-shaped dough had morphed into a small and stiff blob (insert joke here). It was like vaguely-chocolate flavoured hardtack (seabiscuits!). Conversely, everyone else had fluffy, poofy bread. So, I haven't cooked with yeast since then (except when my mum makes man[2] tou[2] (馒头) - steamed buns. It appears that I will never be able to make or taste the magnificent  creation called chocolate cheese bread.

I know a lot about the yeast we use for cooking. S. cerevisiae. They like to grow at 30 degrees C, and they replicate every 90 minutes. They can have a leu2 selectable marker, because they need leucine. Histone chromatin modifications alter viability and growth, with H4K16 and H4K5 being the ones I researched. I'm also sick of smelling them.

Despite all this scientific knowledge, I still can't bake with them. Or maybe I just picked up a bad batch of yeast. Certainly, the yeast isn't dead, because there were bubbles in the sponge (the yeast+ warm water + sugar mixture), and the dough DID rise and nearly doubled in size.

The brand of active dry yeast that I used was Hodgson Mill. Last month, my croissants failed with them too (but that might've just been because I accidentally killed the yeast during the sponge-making? It did rise a bit).

As I sit here chewing this semi-dense lump of cooked dough with puny air bubbles, I wonder what went wrong. Was it the recipe? I let it rise for 30 minutes longer (1 h as opposed to 30 mins), so did that mess up my bread? I used oil instead of butter, but that shouldn't have affected anything. I think it's time I go and bought more yeast. Real bread must be made, soon.

Yeast bubbling, with a dollop of oil.

Bubbles. I'm not sure whether there is enough live yeast.

The dough, after 1 cup of flour.

After 15 minutes of rising in my bedroom.

After 45 more minutes of rising outside in the sun, covered. The dough has risen, and it felt super soft and spongy and..."correct" textured? I've never touched correct bread dough before, but it felt like a soft marshmallow pillow!

After cutting and rolling the dough...doesn't look too promising.

After 30 more minutes of rising, in the oven with boiling water. Looks like it might work!

After baking. The rolls have shrunk. DECREASED IN VOLUME. HOW COME!? This was a huge disappointment.

I end up with something resembling soda bread. It's a bit crumbly, slightly dense, has little holes, and is not the expected fluffy dinner roll.