Enough of COVID...what are you doing to the house?

[GreyGhost]

The opener shouldn't be doing any heavy lifting. The spring(s) should offset the weight of the door so that it can be easily lifted by hand as well as stay in place when let go, so best case scenario, your existing spring(s) may need to be wound a little more to compensate, or worst case like mentioned, you may need new springs.

I'd focus on any air gaps between the garage door and opening, whether you get a new door or not. The door should be adjusted so that it's as flush as possible when closed. This new track system looks interesting in how it pushes the door against the opening:

ThermoTraks | Seals for Garage Doors

ThermoTraks energy-saving seals for garage doors are available for any size door. Our thermal seals for garage doors are the only option for garages with A/C.

thermotraks.com

A similar option that's been around longer is Green Hinges, which have springs to push the rollers against the track to force the door towards the oprining:

Green Hinge Canada - Shop Residential and Commercial Garage Hinges

Green Hinge Canada is the only approved Canadian distributor of the Green Hinge Garage door system. It provides a tight garage door seal, saving you energy & money.

greenhingecanada.ca

I saw a great system on the door of a wood kiln. It would be easy for a manufacturer to incorporate it into a garage door system if they cared at all. Similar in concept to the thermo tracks. As rollers come down, there is a ramp that pushes the door against the seals. Gravity works. In the kiln, there was a plateau at the bottom so the door hung on the wall. That part isn't needed for garage doors.