With the information you shared, what indicates that this is a dust mite problem?
Please consider ventilation (fresh air) because tight new hiomes have many chemical toxins that can create problems (glues, paints, etc...which take time to offgass)
Hydronic heat with the boiler in an outside shed is the best way for heating, but ventilation is essential. If you live in a polluted area you may also need to use a hepa/carbon v bed combo to scrub the air.
What is your family's diet like? The more details the better. vaccination history...medical history, etc.