When you're on insulin you do have to test more. I test upwards of 8 times a day depending. My insurance covers about a box a month, but I supplement that with my dad's because he doesn't have to test as much (twice a day max) so he'll loan me some strips when I'm short. It's ridiculous, but insurance companies will usually only pay for 100 strips a month....which doesn't even work out to 4 tests a day! Perhaps you could call your company and ask them if you could up the allowance if you got documentation from your doctor that it's necessary for you to test more often?
I'm wondering if you shouldn't be on a rapid insulin with the lantus. Obviously the lantus if running you low at such high units, so maybe if you did a lower dosage of lantus and started taking a novolog or humalog based on what you eat then you'd be in better control and not have so many lows? Lantus is a "background" insulin and will keep your overall numbers low, but if you're going too low that's a problem and obviously you're taking too much of it. Rapid insulins like novolog and humalog work to digest the food you eat immediately. Kind of how when someone non diabetic gets a jolt of insulin from their pancreas when they eat.
I don't think I know very many insulin diabetics who aren't on both a rapid and a long lasting. Maybe you could bring this up to your doctor/endocrinologist next time you see him/her
Hope this helps!