Just keep at it - ketosis comes differently for different folks. My research tells me that it’s typically 2-3 weeks to reach ketosis, but it’s not uncommon for some folks to take longer.
Restrict your carbs (not sure what they are, but can you lower them? Recall, 20-50 is typical; some need even less to reach ketosis). Watch your proteins and consuming too many proteins can cause the body to convert excess proteins to carbs, and try to cut back on fats somewhat. When the body switches from carbs to fats for fuel, if we feed it too many fats, it burns them rather than stored fat. Cutting back fats a tad forces the body to burn stored fats - that’s where the weight loss and health benefits comes from.
As for test strips - they’re not the most accurate way to measure ketosis. As we lose weight, they become less accurate. If you’re in this for the long haul, you might consider buying a glucose/ketone blood meter. I like the Keto-mojo meter as it’s quick, accurate, and measures both readings (using one test strip for each).
Hope this helps, and Keto on!