My DSD is 17. On our weekday nights with her DH and I would expect to be told if she wasn't having dinner with us for any reason, or if she was going elsewhere after school just so we know where she is and she is safe. Its just basic politeness for anyone of any age. If I'm going to be late for dinner or eating with friends I let DH know. If she called and said she wanted to eat with friends then that would be fine as long as we know. Fairly sure her DM and Stepdad have similar rules. We wouldn't expect her to be out late on a school night unless there was an exceptional reason. We don't have a bedtime for her, she tends decide herself to go to bed between 9 and 10 on a school night and she gets up for school without a problem so why would we?
I wouldn't dream of taking her phone away at that age. Maybe for a younger teenager, but not a 17 year old.
At weekends she can go out as late as she wants PROVIDED she we know where she is, know she has a safe way of getting home and we know what time to expect her and she keeps her phone on and charged. She does do this, so no drama.
This situation didn't happen by magic, when she was 14 or 15 or so we had a number of arguments about her forgetting to charge her phone, leaving her keys behind, stuff like that, and obviously at that point we would say around 9:15 "it's getting late, you have school tomorrow do you think you should start thinking about getting ready for bed?"
By making her be responsible for the decisions with strong reminders and suggestions she does manage her day to day routine herself now.
She hasn't got a boyfriend yet, so we haven't had that to deal with just now.
I suggest you talk to her about making some changes to your rules now she is older or you risk loosing her altogether.
She is obviously very bright, so ask her questions. Say to her, if I was the child and you were the mum (do you say mom?) what rules would you have?
I bet if you ask her like that she might surprise you. Ask her how many times and for how long she should be spending with her boyfriend in order for her studies to not suffer. Ask her what time she thinks is a reasonable curfew at weekends? Ask her what she thinks would be a fair punishment for a kid her age that went out and didn't phone to let her mum know.
If you can talk this through with her then you can make the rules together and prepare her for adult life.
Her boyfriends mum was rude to you by the sound of it, but however badly she put it she may have had a point.