As long as they change colour its positive. Darker sticks just mean youre a bit dehydrated. Mine are the lightest shade of pink first thing in morning then rest of day they read negative due to all the water. Hope that helps x
To be honest, no, they're not worth it with LT on 100% as you'll definitely be in ketosis if you stick to it. The only time they're useful is when you know you're out of ketosis and you're monitoring how long it takes to get back in. Bear in mind too that they should be used on your first wee of the day upon waking, after that it'll be too dilute and mostly test negative (falsely)
Hang in there, it does pass but its a big change to your routine and your body generally won't give in without a fight!
If you feel you absolutely MUST eat or you'll binge or something I find a tin of tuna in springwater helps (not brine, contains salt) but that's just an emergency measure. Try and stick it, you'll soon be reaping the rewards xx