Where to start with my house?

[Used2bthin]

We bought a 70s semi two years ago. We've never had a large amount of money to spend at once so are constantly chipping away at it but I'm worried we are just wasting time and money.
So far we've :
Put new flooring in the kitchen, dining , extension bit and hallway.
Painted most rooms but the plaster is uneven and skirting boards tatty so still looks awful
Put a new fireplace in.
New bath and toilet

I look around and every room looks shabby as DH has great DiY skills but neither of us are great at painting. The kitchen is getting me down as we want to change it when we (one day) re do and extend the slightly odd garage conversion so it feels like there's no point doing much.
We have artex in all rooms bar one and an electrician said at some point re wiring would be a good idea but it's not urgent.
Oh and we could do with new carpets upstairs.
Where to start? Are we wasting time doing little bits that will be changed with an extension and re wiring on the cards at some point ?

If you can't afford to do up the rooms already there - how will you afford to build an extension? Sorry but this doesn't make sense to me.

If you are not happy with the walls and skirting I would save up and get one room at a time replastered and new skirting

The issue is we can do it room by room (although finding someone willing to do one room at a time hasn't been possible so far) but I'm worried it would be hugely wasteful if we then end up having to rewire and I am going round in circles with it all a bit .
The extension stuff can hopefully done at the next mortgage renewal (18months) but it will change the layout of the house slightly particularly the kitchen.