My second brew saga

Hi all:
I brewed up a 5 gallon batch of American pale ale yesterday which is bubbling away nicely in my fermenting bucket today.
Background, it was a kit put together by my LHBS based on the Brewers Best kit,
The LME was replaced with DME.The owner told me to download directions for the BB kit from their website and I could follow that.
On brew day I noticed he only included 1 oz of willamettes aroma hops and the recipe call for 1-1/2 oz. Not to worry, I just happened to have a 1/2 oz. pack of willamettes on hand so I added it at the appropriate time.
Once cooled I found my OG was a bit low at 1.048 vs the recommended 1.051 to 1.055. I tasted the sample, pretty hoppy.
Now to the questions;
1. Could the OG have been low due to the use of 6lbs of DME instead of the 6.6 lbs of LME the kit would have used?
2. Could the owner have only given me 1 oz of willamettes instead of 1-1/2 be on purpose dues to using DME?
2. will the additional 1/2 oz of finishing hops make much difference and will it be closer to what Brewers best intended or not?
Time will tell on the outcome but just curious about the discrepencies.
Thanks

3.3 lbs of lme = 3 lbs of dme, because of the water in the lme you need more weight to equal the amount of fermentables.

The OG could be of because of the worth not being mixed, did you use any top off water to reach your 5 gallons? That could be also why you might be low.

I did use top up water and actually ended up less than 5 gallons. i added what i had boiled the day before. once i saw the low reading i knew i didn't want to add more despite being less than 5 gallons.
It was mixed well but the turkey baster, and sample tube were both wet from sitting in sanitizer, maybe that helped lower it a bit.