Battery issues since 11.4 update

I have an iPhone SE, which I purchased new in January 2018.

About two weeks ago I did a software update to IOS 11.4

Since the update my battery continues to drain power at an alarming rate.

I am having battery drain problems.

As an example, a few nights ago my battery was charged at 100%, went to bed and in the morning it was at 49%. The next night same thing, 100% at night then 29% in the morning.

I never experience this before the update. I tried turning off certain apps that I don’t use, reduced the brightness of the screen and change my e-mail setting from push to fetch (30 minutes), however, this doesn’t seem to work.

Today I visited the Apple store and spoke to a very friendly lady that works at their Genius Bar. She ran a number of diagnostic phone tests and everything came out fine. She made a few adjustments:

1) Change my e-mail settings to fetch (1 hour)

2) Changed my Battery to Low Power Mode

3) Turned off Background App Refresh

Not sure what the results will be until a few days from now.

Are others experiencing the same issue? Is there a problem with 11.4 update?

Any help would be appreciated .