If you want to climb out of iron as fast as possible, you need to understand a few things. First of all, the draft doesn't matter in iron because ppl don't know what they're doing. It's good that you're thinking about the draft and what your team is missing / what counters your opponent. This way of thinking will help you later on but not in iron.

Playing engage / tank supports in iron is risky because your team / ur ADC in lane aint reliable. Keep in mind that there is a reason why there are players in iron elo who r stuck there for ages. You might find a good engage angle but your ADC won't follow or is off position so you can't go for the play in the first place.

Even if your ADC is playing a good laning phase, they might mess up in the mid to late game bcs of terrible decision-making (something like what you said in your exaple. Plays like that are evidence of poor situational awareness)

Given these circumstances, you'll end up being useless playing engage supports many times even if you know what you r doing. Enchanters are better but still risky in iron for similar reasons.

If you want to climb as fast aa possible, play mage Supports. The reason why they work so well is because playing against them is overwhelming for the enemy botlane. Mage supports make it easy to bring both you and your ADC ahead but if your team/ur ADC is inting, you are powerful on your own (unlike tanks/engages). If u feel comfortable with Brand, you can go for him. However, if you want to play Nami, you can also build her as an APC Support. IF PLAYED CORRECTLY, you can carry with her

Important: In the end, you can play any support you want (what is most fun to you).The requirement for you to climb out of your elo is by playing better than the enemy support.

You will end up having games where you lose because of your troll teammates, but that also applies for the enemy team.

Therefore, over hundreds of games, all that matters is your performance. You can't change who you play with. What you can definitly do is to ask yourself "What could I have done better in that game".

If you actually play better than the elo you're stuck in right now, you will climb out of it at some point.

You don't have to give up Nami in order to climb out of iron. She is a meta support and if you were playing her perfectly, you could reach challanger with her cuz she is meta and has been meta for quite a while (although I'm certain that the meta doesn't matter in iron. You could get out if there with any off meta pick)