Why don't you just add a humidifier to your system via a professional company and eliminate your problem once and for all.

Kill two birds with one stone. Seal the air leaks in your home and the ducts so you will reduce your energy costs and increase the humidity at the same time.

Just a homeowner here.

Do you have a basement? If so, is the humidity higher there?

If that's the case, you could look into adding a return from the basement to your heat pump.

Cheap and simple.

No basement wish I did though.
I don't think I have an abnormal amount of leaks. Just today I had 8" Cellulose added to attic.
This house is all electric 1700 sq ft living space. Highest bill in summer $150.00 and winter less than $200.00.

This morning outside humidity 99% inside 35% I don't think I have a leak issue.

"Why don't you just add a humidifier to your system via a professional company and eliminate your problem once and for all."

While house humidifiers are a very mixed bag with heat pumps.

The lower temperature operation does not pick up as much moisture as a conventional furnace.

Even the misting type humidifiers have problems with heat pumps, the water mist does not turn into water vapor and settles on the down stream ducting causing rusting problems.

"This morning outside humidity 99% inside 35% I don't think I have a leak issue."

Then think. That seems about right for a 40F temp shift where none of the humidity generated in the house is retained. Leaky houses make for dry houses in winter weather when the temp is a lot higher inside than out.

Check the temperatures as well and consult a Psychrometric chart. You might be very surprised. While you are looking for air leaks in the envelope, look for leaks in your ducts. If you have leaks in supplies located outside your house envelope depressurize the home and outside air is sucked in. Leaks in returns outside the house suck outside air in directly and pressurize the living space.

"Leaky houses make for dry houses in winter weather when the temp is a lot higher inside than out. "

this.

The humidity is most commonly given as 'relative humidity,' (RH%) and rarely as absolute humidity (it would be the weight of the water in a volume of air, not a percentage).

The RH changes as the air temperature varies (even though the actual amount of water vapor in the air is the same).

Warm air can hold more water vapor than cold air, so 90% cold air will fall much lower in RH% when it is heated up inside the house.