Reddit mentions of Duck Brand Socket Sealers Variety Pack, 16 Outlet Sealers and 6 Switch Plates, 2 Decorative Covers, White, 283333

I used to do maintenance at a couple medium sized hotels, get a big bag of DE (diatomaceous earth) and a squirt bottle thing (usually comes in a kit with the DE if you're getting a bed bug kit) and spray it EVERYWHERE in every nook and cranny (bed, couch, cushions, corners of floors/carpet/walls), also spray in your car, everywhere, make the cops who pull you over think you're a coke dealer with parkinsons.

Run all of your clothes and couch cushion covers ect in HOT water. And dry on HIGH heat. Bed bugs don't deal well with heat, granted your clothes may shrink...

I've spoken to many pest control people (guests will bring them in) we take a nuke everything/salted earth approach to confirmed reports of bedbugs. They will usually hide near wherever they are going to feed. So bed, couch, etc, anywhere you might be sitting for a long period of time.

They normally don't move from wherever they set up their home (a particular corner of the bed frame etc) until they get crowded out.
Depending on which side your neighbor is, line the common wall with DE as a precaution, also if you do share a common wall with her unit, get those outlet/switch cover gaskets and install them under the coverplates. (I woulnd't spray DE into the outlet boxes, DE itself isn't conductive, but it will pull moisture out of the air, and become conductive overtime).

There could be poorly insulated power sockets and light switches that are allowing air to move through the walls. These are little insulated pads that you put behind your light switch plates/sockets and it may help, at the very least you'll have fewer spots for drafts.

http://www.amazon.com/Duck-283333-Sealers-Variety-Decorative/dp/B0040JH21W/ref=sr_1_1?ie=UTF8&qid=1419703715&sr=8-1&keywords=light+switch+insulation

That is just one brand but it gets the idea across. Your local hardware store will have more options.

This is just from an old renovator. Please take it for what it's worth.....

I have nothing but the highest respect for the eggheads at UMASS Amherst, but real world installations will almost certainly fall below the targeted goals.

I have opened up more walls with blown-in insulation than I can count, and in every single instance there was a void at the top due to settling. Some of the voids were between a foot and two feet wide. Now maybe the 4.5 pound per cubic foot density will alleviate that, but I personally doubt it. None of the installers that I've ever met weigh the product as it gets blown into a cavity. And they don't use a flexible rod to mechanically pack the product down. They get paid by the job, not the hour. They blow and go.

The lofty goals of increased air sealing, zero settling, and better sound control is nice, but in reality will not be easily done, nor will it be measurable. All it takes for a poor air seal is for an interior outlet to not have an envelop around it, especially if it is opposite an exterior outlet. There are special electrical boxes to address this issue, but you don't have any:

http://www.alliedmoulded.com/go/energy

you can seal them with spray foam:

http://www.coupons4lv.com/uploads/1/6/6/4/1664982/9637161_orig.jpg

you can use foam gaskets:

https://www.amazon.com/Duck-283333-Sealers-Variety-Decorative/dp/B0040JH21W

You should also caulk along the seams of the sheetrock where it meets the other walls, the floor, and the ceiling. The floor joints are the worst culprit. I've had some that were so bad the wind whistling through would blow out a candle.

To get to zero settling, I see no way to accomplish that without mechanical compaction. Areas that often get less densely packed are the parts of the void below the electrical wiring. A dam can be created between the sheetrock and 12/2, giving the impression that the void is filled. Yet it is mostly air under the wiring. Sometimes you need to force it past the electrical cable with something rigid, like a thin fiberglass pole.

And there are WAY better options for sound control than blown-in. Try a few experiments with your fake wall with no insulation, loose fill, and dense packed. There will not be a great difference.

In short, doing the best you can is your goal. The lofty goals of the UMASS experts are nice, but not likely achievable in the real world.

Have you added insulation to the outlets and light switches? These little gaskets are cheap and they reduced our power bill by about 10%. Paid for itself the first month. https://www.amazon.com/Duck-Sealers-Variety-Decorative-283333/dp/B0040JH21W/

Socket sealers (in addition to child safety plugs) work really well on any outlets that happen to be on exterior walls.

https://www.amazon.com/Duck-Sealers-Variety-Decorative-283333/dp/B0040JH21W

As many have said, you need to find out here the drafts are coming form, walking around the house with incense is a great idea as someone else posted.

I know you said you have all new windows, but check around the window sills. Its very possible the window itself is fine, but it wasn't sealed properly when installed.

Check all of your electrical outlets and power switches. something like these Outlet Sealers would probably help. they are cheap and easy to install. I installed them in my house and noticed a difference in how draft it felt.