Hi
I work for an airline and managed the risk monitoring for those rays and can say that the rays you receive in flight (cosmic radiation) are not a concern at all for passengers even when pregnant.
Scanners (metal detectors) are not dangerous but x Ray scanners like those at heathrow should be avoided but you can have a manual search.
If you are worried about being questioned, take your notes for info. Not just useful for flying but just in case u need medical help in resort.
If you know that you are nervous when flying let a cabin crew member know even if you feel stupid! They are trained to deal with this and pregnant passengers. Personally I wouldn't suggest drinking when flying and pregnant due the effects on your body of alcohol at altitude however you are on such a short flight you could try it. I use a vino...or two normally to relax in flight but wouldn't when pregnant as I know my body. Plus the dehydration is worse when flying so make sure if you do have a tipple, you top up on water for baby.
At 16 weeks you shouldn't get asked iunless you look further along. I'm off to Egypt at 27 weeks but 28 weeks is the cut off date for a doctors fit to fly note with the airline so for peace of mind I'm getting a note after a pre flight check up just to make sure my blood pressure etc is ok anyway.
For the other posters concerned about long haul flights....I flew to Thailand (11 hours out 13 hours back) at 12 weeks and had to sleep more to get over the time difference. I did a further 4 internal flights. On my return flight my morning sickness was awful so I really recommend getting an aisle seat, moving about in flight and telling your crew you are pregnant and want to ensure you are hydrated they should be able to help if they a good crew. On an airline with complimentary drinks ask for a bottle of water rather than a small cup it'll stop you constantly asking for one!
I had previous losses and had a scan and check up before my Thailand flight and despite my losses they were happy for me to fly.
Enjoy your holidays ladies!! Now if I can find a solution to not looking like a beached whale......