I've been using the same beta reader for awhile now, but lately my reader hasn't been available for my newest book. I stopped freaking out about that around the same time I learned a valuable lesson about writing. Beta readers and reviewers are great, but as an author you should always be trusting yourself...and so should I.
The Issue of Trust
It's good to have beta readers, to get a second opinion, to check your work against someone else so you know you're on the right track. But you can't always rely on these things. The actor writing a novel is always a risk. It's a leap. You're putting something out there that's personal to you, and the world may rip it to shreds. You'll get a little less bloody if a beta reader rips into you first. But you don't always get that option. That's why you always have to make sure you're trusting yourself...and your book.