Booking a vacation, but how and what?

Just book it.
If you get pregnant now, you won't be too far along during the high season this summer, so flying shouldn't be a problem.
Consider getting cancellation insurance just in case (you'd need to check if pregnancy complications are covered).
Also, make sure your holiday destination is close to a hospital, choose a country where no vaccinations are required, and obviously avoid Zika areas.

I had exactly the same situation as you now, 2 years ago. And yes, I was 9 weeks pregnant when we left for Zakynthos (Greece)... Had a great holiday

Xkruimel

By the way, (I think) you're also allowed to fly after 28 weeks of pregnancy, but then you'll need a pregnancy certificate. If you're pregnant, I'd definitely bring it with you on vacation anyway.

I’d also take your holiday comfort into account when booking. When I was pregnant, I had pelvic pain, so I had to consider things like few stairs and a good bed.
I’d definitely look into good travel insurance/cancellation insurance.
And it’s also handy to check whether the healthcare in the country is good. I recently read a story about a woman who went on holiday at 26 weeks and gave birth there. The baby survived thanks to the good healthcare on that island.

We’re also planning for a second child and have deliberately not booked anything for the summer yet. Mainly because of the possibility of pelvic problems again for me, and also because of the Zika virus. There have been stories suggesting it might also appear in the Mediterranean region this summer.

I have 1 tip. Also take finances into account if you're pregnant and going on vacation. I was in Turkey and 8 weeks pregnant when I had complications. This added up to hundreds of euros. Once you're back home, you can get the money back, but you have to pay it upfront first. We thought we were well insured. Our insurance covered these kinds of things abroad and also paid out to hospitals abroad. However, the hospital we were at was aware of this but didn't comply...