This is simple economics RAISE YOUR PRICES!
We have a saying in my family (all service type business owners)
I ok being tired and I am ok being hungry, but I am not ok being both.
Don't work yourself to the bone for little money.
If you are overbooked, drop the lowest 10% of your customers.
You should look long and hard at your numbers and find out where you need to be! It's all in the numbers, they will tell you if you can expand and take on the labor burden and extra overhead or if you are just pricing yourself to low and working for peanuts.
I would first look at all the accounts you have and find out percentage wise, what profit margin you are making on each. If you do not know this number, then you do not know your numbers and true cost/profit.
Once you have that information, implement contracts and reorganize so your service route is the most profitable you can make it. (This will more than likely lose you few more clients)
Your end goal should be that you retain the most profitable clients, with contracts and a favorable more efficient route and free up some more time to pursue even more profitable commercial work.
As a bonus, if you can get the less profitable customers under contract, you can then sell them to the jokers in town cutting yards at $35 a piece...