For asthma is it dangerous to use only your rescue inhaler, especially if you've been prescribed a steroid inhaler to control your symptoms. Asthmatics have died due to badly out of control asthma, where they have over relied on their rescue inhalers. I would not recommend that you do this.
The problem is that due to the presence of excess inflammation, the airways tend to get get hypersensitive and constrict the muscles around them, which in turn reduces the airflow even further. Some have such severe constriction from both inflammation and the airway muscles that there is not enough airflow/oxygen making it to the alveoli. This is also due in part to the incomplete emptying of the lungs. This process can happen over a matter of minutes to days. I don't think that this is a risk worth taking. Plus you lose your quality of life and are no good to anyone.
There must be a balance achieved in the amount of medication you are taking versus the symptoms you are having. Detrimental symptoms have to be treated aggressively. As many asthmatics are young people and have a whole life yet in front of them.
Because of serious side effects I stopped using steroid inhalers and switched to natural anti-inflammatories and mucolytics instead. The only medication I use now is albuterol which I use in a nebulizer. I also have a small portable nebulizer for when I am not at home. This is better for me than a measured dose albuterol inhaler because I only use what I need at any given time. My health is better with natural products than it was with a steroid inhaler.
If you use your Flovent with a spacer, that will help to reduce any side effects you may have. However, I'm really quite surprised that you aren't on a long acting bronchodilator along with your inhaled steroid, it is more effective then combining two steroid inhalers together.
What sort of allergy symptoms are you having to your inhalers? Wheezing after taking it? Or developing hives? It certainly wouldn't hurt to go back to your doctor and try some more of the newer inhalers that are available right now. I think sometimes after many years our bodies can develop a sensitivity to the medicines or are just not as effective anymore.