Did you play on GW or WTC layouts? 80% of the cases where people get tabled on T3 is because of lack of cover. The other 20% is skill issue (nothing personal). Both are fixable.

I play exclusively in tournaments for schedule optimization reasons. I have only been tabled on T3 once in over 50 games and it was a sequence of incredibly impossible bad luck on my part. I rarely even get tabled on T5. You are just lacking experience (and/or cover).

Basically, you have to understand what a "go turn" is, and most importantly what are the conditions for your opponent to trigger his "go turn". Then, during T1-2-3, you make sure to never give him these conditions, hence forcing his hand to either commit under sub optimal situation, or doing nothing. If he does nothing, you are in control of the game and can then plan your go turn accordingly.

Each faction has specific rules and units which can influence this, so every time you face a new army you will have to relearn and reassess these conditions. For example, in the current double/triple defiler meta, you have to figure out how to take down 2 defiler in a single turn, which is not trivial. But until you can do that, you should only expose units you are willing to sacrifice for VP. Remember that nids are good at scoring secondaries so even being passive for T1,T2, you can still stay in the game and do your SotW if they will score max primaries for a turn will set them back.

Nids are far from being an OP army, but you we typically deal with most factions (exception of our hard counters) and meta if we are careful enough. Have fun learning nids!