I reviewed your Anivia into LeBlanc through the level-5 transition, using extracted frames and closer sequences around
  the trades. Your biggest improvement is matching your positioning to your Q cooldown. You land some good responses,
  but repeatedly give her a second opportunity after your stun is spent.

  Times below refer to the in-game clock.

  1. Level 1, 0:51–0:55: the first trade costs far too much.

     You enter beside the wave, take her auto–W sequence, and drop from 705 to roughly 450 HP while she stays nearly
     full. Your Q comes out after she has returned and hits the wave.

     Have your response prepared before entering her threat range: Q into her incoming dash/landing position, then
     detonate while she’s in the explosion radius. If she has already returned and the opportunity is gone, reassess
     before casting. That late Q spends mana and changes the wave without recovering the trade.

     This opening health deficit makes the next two levels much harder than they needed to be.

  2. Before level 2: use your potion earlier.

     You remain around 450–490 HP for a substantial stretch after that first trade, with both potions still available.
     Your first potion becomes active around the next major trade at 1:32.

     Start one immediately after the opening damage. At D4, this is meaningful: arriving at the level-2 contest with
     more health lets you hold your position and collect minions without being one combo from trouble.

  3. Level 2, 1:29–1:34: landing Q doesn’t make the follow-up safe.

     Your Q catches LeBlanc and gets you level 2, then you learn E and follow up. That combination of damage and minion
     collection is useful. However, she still has W, your Q is now unavailable, and she jumps onto you immediately
     afterward. You fall to roughly 250 HP.

     The adjustment is to finish the short trade and create distance immediately. Don’t linger for another auto or
     minion while she retains her return trade. Her Q mark can also be detonated by a subsequent ability, so spacing
     after being marked matters even if you briefly stun her. Riot’s ability description
     (https://www.leagueoflegends.com/en-us/champions/leblanc/)

  4. Level 3, 2:00–2:35: better retaliation, but your health needs to change your decisions.

     Around 2:01, you catch her close with Q and answer with E. That’s a much better response than the level-1 Q. One
     small execution improvement: your level-3 point is still unspent during the response; allocating the second E rank
     before casting would improve the punish.

     Afterward, you’re around 130–170 HP but continue contesting the wave. She eventually eggs you around 2:17. The egg
     survives with your minions nearby, and you subsequently pressure her down to almost nothing—good recovery.

     I wouldn’t automatically call that egg usage bad. But at such low health, collecting another minion needs an
     explicit calculation: can she reach you, and will the egg survive if she does? Otherwise, concede the last hit and
     retain XP.

  5. Late level 4, 3:54–4:00: the clearest repeatable mistake.

     You throw Q through the wave without stunning her, then cast E toward her. She jumps in while Q is down, lands
     chain, and you lose a large chunk of health as you reach level 5.

     Here, keep Q available while collecting with autos or E. If you choose to spend Q on the wave, retreat as part of
     that same action. Once she jumps, move toward minion cover and away from her chain angle; proximity to your turret
     alone doesn’t prevent the trade.

  For your next few games, practice one rule: every Q cast comes with a movement decision. If it misses and her W is
  available, immediately give space. If she spends W and you can answer safely, take your short punish. That adjustment
  should improve both your health and your CS—the early farming difficulty here is partly created by the trades
  preceding it.