milk/sweet stout stuck fermentation? please help

Hi, I have been letting a milk stout ferment for the past 2 weeks or so and my fg readings have hardly changed. We used a bit extra lactose than what one may normally use (and i know that'll add a few points to the reading), but it continues to be stuck around 1.028. I started with 1099 yeast and let it go for about 10 days and it seemed done, but I could not imagine that the extra lactose could make it be around 13 points higher than any calc. said it should be. I threw in an extra safale s-05 just to see if it may continue fermenting and all i got was 1 point drop in a week. Here's the question: is it possible that adding like 20% extra lactose would keep this stout pretty high (its been steady for almost 2 weeks too) in fg? I think its done...do you? or is it stuck?

Posting the recipe and mash temps, etc would help. Lactose does not ferment, but 20% more of what amount? How much did you put in? Could just be done if you had a high mash temperature, lots of unfermentable grains, and of course lactose. 1.028 is sweet, just like a milk stout should be in my opinion. How does it taste? Worst case, xfer, and repitch, or if you have the equipment, do a forced fermentation test (stirplate, new yeast, oxygen etc)

If you added over a pound of lactose I would think it's done. You need to post the ingredients and quantity and mash temp used.

I realize a recipe would be nice, but my "recipe" book is currently lost. it looked something like a lot of the left hand milk stout clones:

7.5 lb Marris Otter
1 lb Caramel 60
1 lb Dark Munich
1 lb Roasted Barley
12 oz Chocolate Malt
8 oz Flaked Barley
8 oz Flaked Oats
18 oz Lactose Sugar (15 Min.)

We used a 1099 yeast and then a safale us-05

However, we used maybe 20% more lactose (and a tad more chocolate malt) to try and experiment and maybe get a "creamier" feeling beer.

Currently I believe that the mash temps were a tad low (tried for an infusion mash in the cooler as opposed to one in the brewpot- around 152 degrees, but I remember it dropping down to 150ish). That said we may have added a bit more hot water- i forget, its been 4 weeks- making the temp higher. I think Ill take the advice as well as my intuition and assume its done. its been stable for nearly 3 weeks in gravity...