You can use Yarndex.com
to find out what the actual guage of the yarn the pattern calls for. Then, you can use it to search for other yanrs with similar guage.
Typicaly, if you want to get bulky yarn you'll double strand worsted weight yarn.
To get worsted weight yarn you'd need to double strand DK weight yarn - so, for your bamboo yarn you'd actually have to quadruple strand it which would be much more expenisve.
I hope you can find something that works!