Troubleshooting Marshmallows

Hi all,

So I tried making marshmallows at home today for the first time and they ended up flat and disappointing, I'm hoping I could get some help?

The mixture looked pretty much like the video I was watching (joy of cooking) until I removed them from the pan. They weren't springy at all, just left a dent where I pressed. Then after I started stacking them they slowly started to deflate. Now they're in the fridge because they were all melting into each other and I panicked.

For reference, I followed the Joy of Cooking marshmallow recipe exactly http://www.joyofbaking.com/candy/Home... (except for the changes mentioned below):

Some points of concern:
- My candy thermometer is old and only goes up till 220... I had to estimate when it reached 240.
- I may have over mixed? I mixed closer to 15/16 minutes on my kitchenaid.
- the gelatin I used may have been at fault. (Please see pictures attached). It expires in December and was opened ~8-10 months ago. I can't use the regular gelatin because of dietary restrictions (pigs - any other animals are fine though) which is why I'm using this stuff. Maybe you guys have a better gelatin suggestion?

I let them set for 12 hours.

They did taste good though! I really wanted to put them in hot chocolate but that's not happening. (See pictures)

Thanks in advance for all help and suggestions!