I fear my workout is not that effective. Don't feel tired after it, don't have muscle soreness, I'm not even close to failing at leg exercises. I'm doing 8 reps legs and abdominals. Is that ok? Should I increase the reps? The push ups are not really challenging even though I'm doing them extra wide. Gonna increase the reps and if still not good enough I'll elevate my feet to add some resistance. Handstand and pull ups are doing fine, doing 3 reps per set now! ^_^ With some air kicks.
Based on this information, your workout sucks. Atleast the legs and push-up department. 8 reps on basic squats? Hell, almost anyone with alright mobility can do that, that's not even warming up.
The main question is, is it challenging? Even remotely? If not, there's your problem. Imagine a spinter training for the 100m dash by a brisk walk in the morning. Or a light 5 minute jog on the field. Is that sufficient? I doubt not.
You got three options.
1) Increase reps and sets
2) Increase exercise amount
3) Increase difficulty
I'd recommend doing 1 first, then when you get to a big amount of reps, 3. Then start over again. 2 if you have something left in the tank.
Gray Cook has a good definition for the third option. There are three ways the exercise feels. First, it's easy. You can do it for several tens of reps without stress or excess straining. Then there is challenging. That's where the reps and exercise starts to get on you after a certain amount of reps. You have to focus and stress the body to maintain quality when gaining quantity. Then there's difficult. That's too hard. Something you struggle to do for only a couple of reps and is not really smart to waste time on yet. You have to perform on the edge of your ability, but in the range of possibility.
Same for push-ups. Unless you are a superman, you should find a way making push-ups harder. Have you tried different variations? Check this article by Nick Tumminello. It has something for every performance level:http://nicktumminello.com/2012/06/top-2 ... ariations/
I was thinking of adding plank before the abdominal exercises. One minute of plank and right after that doing some leg raises.
Sure. Planks are an awesome exercises. Remember that there are several great tricks to make it more challenging after things get easy.
How to know if my muscles are really worked out?
How do you measure your progression towards your goals? Do you make progress toward the thing you want? If not, change something. There is no one workout certain answer that's quaranteed only when you have a good workout. If there would be such a thing, things would be easy. But no, it takes weeks and hell of a lot of working out.