Welcome to the forum and to the cheesemaking life!
I'm rather short on liquid rennet and will only be milking for a couple more weeks, so have been reluctant to buy more. I've been making my cheese lately using Fankhauser's methods (http://biology.clc.uc.edu/Fankhauser/Cheese/Cheese.html
) and have found that Junket rennet does fine, if you first allow the milk enough time to acidify. The first time I tried it, I warmed my milk to about 90 degrees before adding my culture, wrapped it in a towel to keep it warm over night. It had already coagulated by the next morning and made some awesome (and LOTS) cream-cheese type product.
Now, the method I use is to warm the milk to about 68 degrees, add my culture, and allow to sit overnight. I then warm to 90-96 degrees (depending upon the recipe) and then add well-diluted Junket rennet to the milk. Two tablets in a half cup of cool water, allowed to sit for 10-15 minutes, sets up five gallons of milk quite well. It does sometimes take an hour or so, but I just coordinate it to set while I am doing chores/milking or some other task so that I'm not watching it. Like water and boiling, you know?
Anyway, don't lose faith. Some cheeses turn out, others don't, but it's always an adventure. Who wants predictable anyway! You may very well be pleasantly surpised by what you think may be a disaster.