What if I wasted 2 perks? And I haven't save. Will it be a big problem near the end of the game and at high levels? Should I re-play 15 levels? I game really slow due to my work...
You can have over 80 perk points untill you hit the level cap so I wouldnt worry about it. I myself have spent perk points on useless perks so I wouldnt worry too much about it.
But to get those 80 perks you have to level up to level 81. Personally i run out of of non-random things to do before reaching level 50 (eagerly awating DLC and quest mods ), so i modded the game to give me two perks points up to level 40 and none after
Anyway, character's power comes from the perks, so wasting them is not a good thing. However wasting two points isn't disastrous.
If you have one point in Overdraw, get Eagle Eye. That way you can zoom when using the bow. It's always good to soften up some enemies while in a dungeon.
No problem. The game is not made to be min/maxed, it is meant to be played naturally and therefore a little sloppy. You're supposed to relax and enjoy the ride instead of worrying about numbers, and it really works. We're so used to being point obsessed but with Skyrim you don't have to unless you want to be an overpowered demigod but that gets boring quickly (hence the kiddies on here saying it's too easy).
If it bothers you tho, remember that no perk is truly wasted since you gain something from every perk, and chances are you'll eventually change your playstyle and come back to that tree and be glad you started it.
I wouldn't worry. I put points into the left side of smithing because I thought I could make plate versions of every armor type with the appropriate perk. Hasn't really affected me.