Is my English bitter ok?

Ive be been brewing an coopers english bitter got Bout 3 days now at a constant temperature of 68F. My OG was 1.032, I checked it today and it was at 1.020 and I tasted it and it tasted still pretty flat but did have carbonation and had a hint of a metal aftertaste. I looked at the brew and it did have some dark brown pieces on the top. Anyone know if all these symptoms are normal?

three days is too soon to know anything and it's most likely fine. come back in two/three weeks.

Most anything will taste like ass at 3 days. Try 3 weeks. Floating things, farty smells, brown foam all normal stuff.

Stuff on top is just hop material and leftover krausen. No way your beer is done in 3 days. Give it another 3 weeks, and let us know what the gravity is then.

Enjoy!

I was told to take an FG at 4 days then to bottle it? is that wrong?

You can bottle when you get steady FG readings over several days. While it is entirely possible that your beer could be done fermenting in 4 days, it is a good idea to let it rest for a while before bottling, first so that you know fermentation is done, and second so that the yeast have time to clean up the beer. If it isn't done fermenting in four days and you bottle, you can end up with bottle bombs. Let it sit for a while before you bottle. You have a low gravity beer, so you can probably get away with letting it sit for a shorter period of time, but patience will be rewarded.

There is absolutely no reason why you would take a gravity readin at 4 days, unless you aren't seeing visible signs of fermentation. You can do it if you want to, to reaffirm that you are indeed making beer, but its not neccesary. If your fermentation is off to a good start there is no reason to believe that your yeast isn't going to fully attenuate, unless it gets too cold and stalls or you have a stuck fermentation. Both of which happen about once for every 20 threads started about it.

I've never bottled earlier than 10 days and recommend the same unless you like bottle bombs. Although they are exciting the beer is hard to drink.

You do understand that it will be flat at the end of fermentation, and you need to add priming sugar when you bottle to achieve carbonation.
And yea let it sit another week and then check the gravity.

It's absolutely fine. I never even bother to check it before 10 days, then usually take a reading on day 10, day 12 and day 14 to make sure it's finished. I'm doing a bitter myself at the moment, 1.032 is kind of a low O.G.. did you follow their recommendation of '500g dme'? I stuck an extra 500g of dme in on top and then 230g muscovado... and I still only got 1.040. I'm expecting around 4% on mine I think.