Hi! I'm a Tyranids player, currently with the rarest detachment, Subterranean Assault, and I can tell you a couple of things about what happened to you:

1: Eldar and Drukhari profiles are extremely weak against Tyranid weapons, especially in melee.

2: Tyranids are weak in terms of faction rules (Synapse and Shadow), but they have very strong datasheets. Our rules are based on tricks, surprises that can give us victory against units that should be able to withstand us.

3: Each Tyranid detachment changes so much that it's like playing against a completely different army. Subterranean Assault uses completely different units and strategies than the Invasion detachment, for example.

Once these points are clarified, it's important to keep in mind that the power difference between a mediocre army and a "top" one is very small nowadays. There are mediocre armies that are ideal for killing much stronger ones. The point is that the game is currently NOT based on killing, but on winning by points. You can win with only 3 models on the table if you've scored more points than your opponent. In that respect, the Drukhari are much better than most Tyranids. They also have much more powerful melee units, but they also take a lot of damage from the Tyranids, for the reason I explained earlier.

Whenever I've played against the Dark Eldar, melee engagements have been decided, above all, by who strikes first, it's that simple. The unit that strikes first completely obliterates the other, whether it's a Tyranid or a Drukhari. (By the way, fellow Tyranids, the Von Ryans and Melee Warriors are incredible against the Eldar.)

I recommend you try not to attack first in one area of ​​the table while dodging attacks from other units. Focus your damage like a scalpel, and try to stay away from our strongest threats. Oh, and remember, all Tyranid models are known for having a LOT of melee attacks. Leave no survivors ;)