as for the thread being (too thin) just pick up a heavier weight thread---even hand quilting threads come in different weights--some people quilt with a 60 wt thread-(fairly thin) some prefer a 30 wt---much heavier---which did you choose?
you can use any thread you like for hand quilting---the only *rule* is to never use a specific for hand quilting in a machine--because often they are coated and will mess up a machine---but it does not have to be specifically for hand quilting ---some people quilt with silk thread!
choose a thread you like- in the color you want---in the weight you prefer and go for it.
and to keep from tangles only use pieces about 18" long- i know there is a (want) to use a longer piece so you don't have to re-thread your needle so often---but it is faster to re-thread than it is to untangle...some people will thread 4 or 5 needles at once and have them in a pin cushion---instead of having to stop & re=thread so often- but the shorter lengths will be much easier to work with.