Hello @rosie1980 and welcome to the forum!
Sorry in advance for the length!!!
I quit apologizing for that a good while back. 
I can’t speak directly to the urine strips … I haven’t used them. You’ve already gotten some input and doubtlessly will get other opinions on that. Some say you don’t need to measure at all, I’m in the camp that uses a blood ketone/glucose meter. The meters themselves aren’t very expensive. The test strips are a little pricier. You can get by without measuring … I like to know.
I’m meticulous about weighing all the food and I’ve spent hours making sure the recipes we have been following hit our macros for the day - we both have the same stats so it’s been quite easy in that regard.
We have been using recipes from ruled.me - i’ve been recreating/logging them with the ingredients we have been buying in MyFitnessPal - some of our ingredients must differ in the UK from the US as some of the recipes have worked out at different macros - so i’ve been logging what we have been eating rather than what has been posted on the website to make sure our macros are accurate.
You stole my usual thunder with the above two statements. . I normally advise people to measure what they eat … both in terms of weight … and work out the macros for yourself. I too have used recipes i got off ruled.me and when I take the ingredients I used and calculate the carbs, calories, etc, - I get different numbers … not significantly different … but different. I’m what some might call a wee bit obsessive, but starting out, you want to know for a fact exactly what is going into your body. How do you know that if you don’t measure and confirm. Once you know exactly what and how much you’re eating you can eliminate some key things from the equation*. I put an asterisk by equation because I believe the short answer to your questions is going to be “It depends”.
Before we go back to the pee sticks (it’s amazing the different topics we discuss on this forum) , let me just say that it appears you’re doing the right things. I’m 10 weeks into keto, I had … looking back … probably 25 pounds to lose … which is a LOT on my frame.I’ve lost 7 pounds in 10 weeks. Took me 3-4 weeks for my blood ketone strips to start showing consistently above 1.0. (Dr,. Stephen Phinney is very good on the topic of blood ketones and his famous chart is posted several places on this forum. Spoiler: If you’re above 1.0 on blood ketones … you’re doing ok … more is not necessarily better)
Some people are slower to react than others. I guess there can be several reasons, but the important thing is as long as you’re sure you don’t have any sneaky carbs entering your body - and it sounds like you don’t - it may just take a little longer. The best advice I got … and I didn’t want toi accept it at the time - is t otrust the system and wait. Most of us don’t like to wait. We live in a society where most things are instant … or t 2 days away in the case of Amazon prime.
Sooo … best advice I have … and I’m sure you will eventually get better/more complete advice is to trust the system and keep doing what you’re doing. Make sure your carbs stay under 20 … it’s a good general target. some people can go higher, some have to go lower, but two weeks is too small a sample size in my opinion.
If you really want to measure ketones … I’d suggest splitting the cost of a ketone/glucose meter with your sister. With two people buying strips, the price comes down some and after a while you may not use that many. I and a few other mildly obsessive types on the forum have used the glucose strips (a lot cheaper tahn ketone test strips) to measure our reaction glucose/insulin (guestimated) to different foods and beverages.
I’ve searched exhaustively for the hard and fast keto rule book. I think it’s been misplaced. Think of “The Code” from Pirates of the Caribbean. “More like guidelines”. There are some extremely knowledgeable and helpful members on this forum that will help you find your way, but in the end you’ll be using the guidelines and finding out what works for you.
I’d probably stop sweating the pee sticks and keep doing what you’re doing, read all you can and then read some more (the search function is your friend) and enjoy the ride!
No apologies for all the words 
just the 2 cents worth of one man sitting high up in the cheap seats of life