I don't know anything about swimming workouts but I wanted just react to your question about not losing weight.
It seems to me that with your workout you are building a lot of muscles especially now that you started doing weight workouts after swimming.
Now are muscles heavier than fatt! So I am sure you are definitely losing fat and as you have noticed yourself become slimmer. However your scale does not tell you that because I think you are building up lots of muscles at the same time! So maybe you should just forget about the scale and trust your and your friends' eyes
Keep enjoying the swimming!