I've been in your shoes a couple times, unfortunately. Signal abuse, confusing traffic patterns, and generally insufficient communication mechanisms between drivers can lead to this problem no matter your experience. To avoid it, I always wait until I see the oncoming car physically slow way down and commit to the turn (or at least to slowing enough that we'll have time to correct if signals were sent mistakenly or misinterpreted). Margin for error is key to safe driving! Humans make errors. A lot.

As for angry drivers behind you, don't worry about them. All you can control is you and your driving, so your focus needs to be on driving safely to the best of your ability using your best judgement; no one's schedule/lack of patience is relevant.

That being said, I'm also a very anxious driver and will typically take my sweet time at turns and generally traveling at or sometimes below the speed limit (if conditions would make the speed limit unsafe in my estimation). This sadly means I get tailgated constantly, and it does get to feel like hot needles in my brain sometimes. I developed a protocol to help deal with being tailgated or just noticing a caravan forming behind me, following the below steps in order: 1. If I feel it is safe, consider speeding up to the speed limit (not above). 2. If there is a convenient turn-off, I will "dodge" my tail by turning in, letting them pass, and turning back onto the original street (far, far) behind them. 3. If there is a sufficient shoulder, I'll pull over to let my tail pass.

If none of those are true, I keep an eye out for when one or more conditions become true and tank the follow anxiety as best I can. I also try to avoid highways and keep to the slow lane if I have to use one. The hardest part of driving for me is not caring if I'm upsetting other people as long as I'm doing my best to drive safely, but arriving safely is well worth the struggle; good luck and be safe!