Is my phone encrypted with my password? I have a Galaxy S5 running LineageOS 14.1.

The device settings state that the device is encrypted.

I set up a password, and select to require password at boot.

I then set up a PIN for unlocking the screen, but did not select to require PIN at boot.

When I boot the phone, it does not ask for the password to boot and only the PIN is required for unlocking the screen.

Is my phone encrypted with my password?
You device is encrypted, but PIN is used for unlocking master key.

From

I set up a password, and select to require password at boot. I then set up a PIN for unlocking the screen, but did not select to require PIN at boot.

we can assume that you wanted different lock screen &amp;&amp; encryption passwords.

Because you are using LineageOS, acquiring root for ADB is not issue.

For achieving what you presumably intended 1st define lock screen password or PIN - select Require password/PIN to start device. Lock device &amp;&amp; do a power cycle - not every1 will agree with this procedure, but I tend to verify.

After successful bootstrap, for different encryption password you should either change password via ADB or terminal or purpose built application - 
SnooperStopper or Cryptfs password manager

If you preffer ADB or terminal, while in shell, issue

adb root && sleep 2 && adb shell "vdc cryptfs changepw password [curent PIN/password] [new password]"

and hit return; if terminal is only option for you, issue only vdc cryptfs changepw password [curent PIN/password] [new password]

You should always verify PW with

vdc cryptfs verifypw [PIN/password]