Oh God, I really feel for you. Please try not to worry & know that it won't last forever.
Our toddler was exactly the same for several years - he suffered with really bad viral induced wheeze & always seemed to be catching a cold/cough which would set him off. It was the scariest time ever & so exhausting - he was constantly in & out of Paeds ICU.
He was referred to a Paeds specialist to try to control it better. He took various preventer inhalers & at one point was on Montelukast for 6mths or so. I'm not convinced it made any difference, to be honest. It certainly didn't appear to give him any side effects, though.
He was also on a low-dose antibiotic for the Winter 3mth period one year & that didn't really have any effect either.
The best approach ended up being Prednisolone - it was an absolute Godsend- the only thing that helped. The Paeds doc convinced the GP to prescribe it for him & re-fill it as & when I asked, without necessarily seeing him, so I always had some in the bathroom cabinet.
I knew the early signs of an attack really well & used to get a dose into him ASAP then tail the dose off over the next few days - that, along with regular doses of ventolin, watching him like a hawk & co-sleeping to monitor his breathing through the night (= no sleep whatsoever!) was the way we got through it!
It would always kick off in the middle of the night & he'd get very bad, very quickly, so having Prednisolone in the house without having to wait to get him to the GP the next morning was essential. The side effects of it horrified me but, fingers crossed, it didn't seem to have any adverse effect on him at all.
If it's any consolation at all, he grew out of it by the time he was around 7yrs old. At one point, I seriously never thought he would - it was relentless.
However, he's now a super fit, healthy, sporty 15yr old, who's almost 6ft tall, with size 10 feet, so the 'stunted growth' Prednisolone side effect certainly didn't come to pass!