Do you even know how fast her Energy recovers?
The base energy regeneration is 10 energy regenerated every second (50 per 5s), effectively requiring 20 seconds to regenerate the entire 200 energy pool.
In other words, just to cast one Q, she has to wait 10 seconds. If she wastes that ES on throwing Q's to heal, she can't sustain Energy for W or E.
The ONLY part of her kit which recovers ES is her passive, which requires her to skill a champion, and then go outside the circle that forms, and then go back in. The most efficient way to do this is to E (and hit E) which refunds the cost of E. (E costs 30 Energy, and Passive refunds 30 Energy).
In other words, she's pretty reliable on only having 1 Q per 10 seconds, and 20 Seconds of skilling nothing to get a chance to heal on Q, of which the heal is friggin small.
If a tiny heal every 20 seconds at MAX is enough to knock you out of a game, you're playing mid wrong, especially since it denies her the ability to skill in the meantime.
I am guessing..... because I don't know exactly when you're complaining about, what level Q, and items she had or runes she had, or more specifically, when I wrote this. At Tier 3 Q The heal is 30% of her premitigation Q damage..... once..... which at level 6 is about 171 damage. So..... she heals for about 51.3 damage. Out of 962 HP.
That's pretty precise numbers.