I tried to play medic today to see how it will affect my rank [...] ( 3 kritz 5 ubers )
Two tips for your medic tactics, since you seem to need them.
a) DON'T use critzkrieg! It's only good if you have a skilled medic that doesn't die and a skilled partner that knows how to kill. If either the medic or the partner doesn't know what to do, don't use kritzkrieg, it will get you both killed.
b) Find yourself a decent heavy and stick to him. Ignore all the whines other people might direct at you because of this. Staying with a heavy is the best way to learn how to play medic on publics.
I know more or less how to play medic, problem was only decent player on my team to heal was Wildblaze, and he went sniper after few minutes

Rest of the team was just bunch of backburner pyros, spies engis and scouts.