I'm sorry for your issues. I can tell you this site is definitely worth it once you figure your way around it. There are tutorial videos that help get you started and a whole lot of fellow workers on the forum to help you get started.
Given the number of tasks you worked, I'm wondering if the issue is your history/cookies got cluttered which interfered with the crediting process. If you search, you'll find several posts recommending clearing your browser history and cookies every couple tasks before working a new task to be on the safe side. I know I do this and it does increase your chances of being credited.
The other thing to watch out for - depending on which tasks you are working - is some companies post a variety of offers, but there is fine print indicating you will only be credited for one of those offers (usually they have verbiage like - only get credit one per IP and user). If that's the case, you probably were credited for the first one, but then any others you worked from the same sponsor were not credited as you already received your one from them. Those are sometimes tricky, but I've noticed the descriptions are getting better at stating that.
Offers don't always credit for me, and some offers may take a day or two to credit. I hope you are patient and continue to give the site a chance until you find what works consistently for you.
Good luck!