Went through this with SD, so I hope this stuff will be of some help to you.

Windows in her room were locked with these:
https://www.walmart.com/ip/Prime-Line-U9823-1-White-Extruded-Aluminum-Sl...
We put them in and tightened the thumbscrews with a freaking set of vise grips.

Deer/game cameras set up in the bushes. Caught her going out the window in her brothers' room and out the back door. Also caught a male midnight visitor coming in the damn window.

Fishing line strung up in places you know they're crossing a fenceline or shrubs.

Internet access was taken care of with a Wifi password that was not given to her at all. TVs and all electronics are easily taken care of with a small TSA type padlock run through the hole in the plug. Also, be open with the school and local library about limiting internet access. It's not as shocking to them as one might think.

Safes:
We are gun owners and have 2 large gunsafes. All sharps were locked in. Razors, kitchen knives, meat forks, food processor blades...all of it locked away.

Self injury.
SD was a cutter and when she lost access to razors and knives, she chose instead to burn. Put a bobby pin on a hair straightener. When that was taken, she moved on to breaking pens and mechanical pencils, using them to harm. They do this as a control mechanism, because the pain helps them in some way. Offer rubber bands and encourage her to snap them on the arm. It doesn't cause permanent damage.

Medication.
DH and I were both med nazis. As in, here's your pill and water. Open your mouth and lift your tongue. Then, don't let her go to the bathroom to barf it up.

My SD was abandoned by her mentally ill mother (bipolar). She made her first threats of suicide at the age of 11. Pathological liar, narcissistic personality. Hospitalized 7 times. Residential treatment program for 4 months. Diagnosed with possible bipolar at 16; doc wouldn't dx officially until 18. Lots of different meds. Made up all sorts of lovely lies to gain pity and gifts from grown ass men on the internet.

You can PM me any time if you want or need to talk.

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Just looked at your profile. Depending on the age of your child, keep a very, very close eye on them. I have 2 boys with DH. They were mentally and physically abused by SD. The physical abuse we caught every freakin' time. Some of the mental stuff we had no clue about. She actually told OBS that she would kill his cat if he told on her about his seeing her stealing razors from our bathroom.

Also, be wary about rumors/lies. SD came up with some doozies, including false claims of rape against one of her friend's brothers (copied word for word out of a book) and molestation by family members who she had never even been around alone (they live 1500 miles away).

On the technology issues... Google has a new router system that allows you to put wireless internet access points in multiple rooms to ensure better coverage (https://smile.amazon.com/Google-Wifi-system-set-replacement/dp/B01MAW229...). It replaces your wireless router, so there's not a provider change or anything. It comes with the option to "pause" certain devices. You can even "pause" groups of devices that you identify. We have found this to be a great way to ensure that one child does not have access to wifi without our permission. And it can be modified from home or out in the world, which is great, too. We use this for TV access, as well, since the TV to which he has access is internet-based (for whatever reason!).

On security cameras, Nest Cams (https://nest.com/cameras/) are great and relatively inexpensive (we have the $199 versions). The outdoor ones have great definition and also capture audio. They're also surprisingly small, which means you can put them anywhere. We have one that monitors the whole front of our house (except the front porch, where there's another). The indoor ones are great, too. For $50 a year (each camera), it records and uploads to Nest servers, as long as you have wifi, which you can access from anywhere.

On birth control for a teen, I would looks seriously to a norplant or an IUD. No effort on her point, but not permanent, either.