I’d buy a much wider wooden curtain pole ( cheap from screwfix and dunelm ) and put high up near the ceiling. Much wider than 150, you probably have 30cm to the left of the window alone, so maybe a pole of around 180cm +. Remember there will be a finial on the end , the curtains don’t pull all the way .
I’d make full length curtains of one or 1.5 width each side ( assuming fabric is 140cm wide ) , with 6” pencil pleat tape. I wouldn’t line then unless the fabric was very thin ( this is much cheaper ). I’d only close them in the summer when the mornings and evening are very light because the radiator won’t be on then.
If you pull them now ( in winter ) they will block the heat from the room.
Then I’d get a blackout roller blind - cheaply made to measure on eBay. The correct size will block out a lot of light.
I’d choose curtain fabric thats not very babyish or a children design, so you don’t have to change the curtains soon eg a plain colour or self stripe , anything that won’t date. I’m assuming that DD is a baby as you have a changing table , so she could get 12 years out of them.
If you DD is a really bad sleeper, you could always get blackout lining, which makes curtains much heavier and will hang well but cost more.
Tall and wide curtains will make the room look bigger and more stylish and give you much more light. You are losing lots of light with the existing blind.