Oh our first one I was a very anxious first Mother lol - slightest little thing. I think it’s fairly normal. But he sounds absolutely fine. Please don’t worry about over feeding him. They just take what they need. It’s rare to see an overweight hamster and they are ones who often live in tiny cages with very little exercise and fed too many sunflower seeds as treats.
A teaspoonful isn’t very much. A dessert spoonful a day is about right. He won’t eat much of it and most of the food they take gets hoarded - then they snack from the hoard. They are funny in that they usually won’t take “old food” that’s left in the bowl. So it means putting fresh out each day. I usually top the bowl up for a day or two then Chuck anything left and start again. Seems a waste of food but it’s not that expensive and a bag tends to last a long time.
This bug situation must be driving you bonkers. As you only seem to find them on the house I’d swap the house out. Tissue box will be fine
. Easily replaced as well.
Taming is time and patience and it sounds like it’s going fine. I sometimes think they don’t get fully tame till they’re almost a year old when they become more mature and confident and laid back.