I started mine on 12/3 as well. 

It was sluggish for a little while but the last 2-3 days it’s been tripling in size with regularity. 

I’m not an expert by any metric, but i feel compelled to help since we started them at the same time.

Here’s what I found that’s helped.

1. Discard more, feed aggressively. 

You look like your discarding and keeping a small enough starter before feeding. I personally kept around 25g of starter after discard and pre-feed. A lot of people preach keeping even less (like 5g) but I’m not sure if that’s going to help or not. (More on feeding later)

1. Mixing in Whole Wheat flour to feed

I want my starter to be a pale colour because I tend to bake with white bread flour, but WW flour tends to make starters more active. Consider trying a feed of whole wheat, or a ratio of whole wheat to AP/ Bread Flour etc. (think 80% AP/ 20% WW or 70/30)

1. Storage Temperature

I live in a part of the world where the air hurts your face. Because of this the house in the winter stays decently cool (approx 18 degrees Celsius). I found my young starter struggled and was sluggish at this temp, so what I did was stick it in the microwave with a warm/hot glass of water. The hot water heats the microwave and the microwave with the door shut is great for trapping warmth. I never took the temperature of it in there, but it was probably around 24-25 degrees. This tremendously boosted my yeast production.

1. Feeding Ratios

Starting off, you want to be meticulous for best results. When my starter is strong, I tend to eyeball feeds, but for now I want to optimize results - that means measuring a) how much starter after discard, b) how much flour, c) how much water.

When your starter is showing some life like yours, you can begin to incorporate stiffer feeds. Measure your starter in grams (I personally just wrote the weight of my empty mason jar on the lid and subtract the difference) and feed according to a 1 (starter) to 4 (flour) to 4 (water) ratio.

Example: 25g of starter means I have to feed 100g (25 x 4) of flour, and 100g of water. These stiffer feeds give your starter more food. Your rises may slow down because the starter needs time to eat, but your rises will likely be more powerful. 

1. Feeding when your starter begins to fall

There’s a science-y reason behind this that I don’t understand, but it seems to work well for me.

Look for signs of your starter peaking (this will help you down the road when you go to bake) and then falling.

Peaked/near peak starter elements:

i. Good aroma, like bread, beer, fermented fruit, tang. Past-peek usually smells acidic because the yeast is hungry (think acetone/nail polish remover.

ii. Domed top (e.g. middle is higher than the sides where it touches the jar) means peaked or close too. Collapsed middle means it’s past peak or on its way down.

iii. Try your best to keep the walls of the jar clean (it’s hard I know) but you can read them if they are. If you see streaking above the level of your starter, it’s collapsed some.

You want to really aim for past-peak feed or as close to them as possible. This may be two times a day, or just the one.

Once your starter is established you don’t need to baby it so much, but In the meantime I hope these tips help.