Well the first days I started taking metformin, I felt really tired during wo and they suffered for maybe a week but I didn't care and kept pushing, added more carbs periworkout and it worked.
Metformin changes completely how your body uses carbs so, the first days your gut is adjusting to it, and it's normal to not feel the usual energy, because your body isn't absorbing carbs that well, but in... Let's say a week you will be fine.
Taking metformin at slow release is useless since metformin works for 36h straight, not to mention taking it twice a day even more useless.... Just take it once a day and before bed.
The dose should fit the carbs you eat.... Usually 100mg Metformin every 100g carbs is perfect.
I doubt that you are currently eating 750-1000g carbs Ed.
You can take up to 3g Metformin per day to curb appetite but this will lead to acid reflux and only baking soda or high dose glutammine can fix it.... I doubt that you are using metformin for that.
You can't say how something works in just 5 days if usage wait at least one month....