My own sourdough bread

Hi all, this is my first post on this forum. I've been an enthusiastic home baker for some years now, also a big fan of pizza making ;). About a year ago I started my own sourdough culture using the pineapple juice method from the BBA. Tried some breads with it back then, and a couple of months ago, but they never were what I hoped. 
Did refresh the starter several times, but it did have periods of sometimes weeks without refreshing in the refridgerator. But this week the sourdough bug got hold of me again, and I decided to try making another culture. Alongside that I decided to test my old starter. So I took 80 grams of that and tripled/quadrupled it. Left it out over night, then added some more flour (bringing the hydration down to 75%). This started rising very fast! 

Tried to bake some bread with it, first a white bread, that was fine, but not spectacular. Yesterday a 100% whole wheat one. Baked it in a loaf pan. Was a bit too dense for my taste. But today I made a 50% whole wheat/ 50% flour one. 
I started with 112 grams of starter I refreshed the day before and put in the refridgerator immediately after doubling in volume. To this I added 260 grams of whole wheat flour and 260 grams of water. Mixed it up and gave it a couple of hours. When this had become bubbly I added 260 grams of flour and 122 grams of water (bringing the hydration to 75%), 20 grams of pumpkinseeds, 20 grams of sunflower seeds and 20 grams of linum seeds and 1.5 tsp salt.

This I kneaded with a handmixer for a couple of minutes. I then balled it up and put it in an oiled bowl. After this had risen I reballed it and put it in a banneton for proofing. Proofed for a bit more than 2 hours. Baked on a stone at 190 degrees Celsius for 50 minutes.