I'm unsure if you understand the differences between a small, MTL setup and a major cloud chasing setup.
With asthma, you'd be better off sticking to devices that offer a lower AMOUNT of vapor, but a higher nicotine content.
My guess is that you are not using your device correctly somehow. With that said, we need more information to figure out where the problem is. You may be able to vape it but as a new vaper with asthma, I wouldn't suggest a mod that puts out a ton of VG, persons with lung issues of whatever sort often need a higher PG content juice and a FAR weaker delivery system. You may be able to use your current mod with the right topper, and just enjoy VAST battery life, so fear not. You haven't WASTED all your money, but you need a different atomizer (the tank that goes on the mod) and you need LESS power, and more nic and PG.
I would suggest buying either a Nautilus 2 tank, or an Innoken Zenith tank. Both good sturdy easy to use (more or less, watch some YouTube videos on your gear and/or get educated here) and go with something that will not overwhelm your system. FWIW, I cannot STAND high wattage, high vapor setups. I don't like them and I'm never going to. I am still a successful vaper, nearing a year smoke free. A lot of vape shops like to tout "high vapor" setups but they are not for everyone. You need the right gear, the right liquid, and I'd imagine that you can meet with success. There are many successful vapers with asthma or starting vaping with lung issues, I was one of them (nearing a COPD diagnosis). I was able to make vaping work regardless, WITH the right gear.
Keep asking questions but let us know what you have currently and how you started using it, I'd imagine we could offer more help.
Anna