@Imogen11 , don't worry about a thing, you are doing everything just right!
Undoubtedly, being here on the boards you learn a lot, it is a great place to become aware of issues and to stay in touch with fellow hosts. But it also can raise your anxiety levels when you read one horror story after another - so take it all with a grain of salt and trust your own instincts more than anything 🙂
There are a lot of newbies out there who have no reviews, nothing in their profile. It really doesn't mean much one way or another. If you want more time to perhaps exchange a few messages back and forth with potential guests, temporarily take off IB and see if that makes you more comfortable. As it is, having IB on but requiring previous reviews, a lot of guests have to send you an inquiry anyways.
even if there are previous reviews, it doesn't say much: a lot of hosts leave very nice reviews, even if they complain about their guests here. So it always comes back to using your own best judgment. You only get the last name of the guest after the booking is confirmed, so really, how much research or vetting can one do before?
One thing you might want to consider is lowering the number of guests allowed: lots of hosts are trying to make their place avialable for 6 or 8 or more guests, offering to pull out air mattresses, etc. If you get plenty of bookings, limiting it to 4 would be much more peaceful....especially with 1 1/2 bathrooms.
anyhow, happy hosting and good luck to you!