Welcome to the hobby/obsession. Brewing is a lot of fun.
Krausen is supposed to blow off. Getting stuck in the airlocks or tube can happen. Ideally, the airlock or tube DOES NOT get clogged, because, if it does, it blows off! So, if your krausen isn't "moving along"--that could be a good thing (it means no blockage). CO2 could still be burbling past. Of course, you'd probably have been seeing bubbles in the bucket that the hose was inserted into...
Hydrometer, Hydrometer, Hydrometer.
The only way you'll know if things are progressing along (fermentation-wise) is to check the SG. Sometimes, the fermentation only seems to take a few days (due to yeast strain and/or temps). You'll have better beers if you control fermentation temps, and fermentation will take a little longer, usually. (If you don't already have temp controls of your refrigerator look into Ranco or Johnson controls online along with "DIY how to wire your Ranco controller" on BrewBoard).
The bitterness/astringency could be due to the grains (roast grains that are mashed tend to lend a lot of astringency, esp if oversparged and pH allowed to >6.0) See other posts on tis forum about cold steeping dark grains or adding it to first runnings only.
Bitterness? Might be due to hops ending up in the fermentation bucket. Or taking a long ime to chill the wort (ie., w/o use of a wort chiller) leading to increased hop utilization.
Another thing to consider is your local water profile--if it is excessively alkaline (unlikely for an oatmeal stout utilizing dark grains), it could be conributing to the problem. What does the sulfate concentration look like?
Is it a process problem? Check your sanitization and rinsing. Describe it for us.