If you’re not familiar with the bootstrap, this introduction might help you understand what is going on (essentially, you use a different method to estimate sampling distributions, which p values rely on):
For a more in depth coverage, including a dance of confidence intervals, there is more here:
Depending on the number of bootstrap samples, you might get a different p value if you run the same analysis again, because of random sampling. But irrespective of the p value and confidence interval, you need to describe your effect sizes (slopes in your case) and put them in context. Here are two very useful resources to report frequentist results:
https://www.tandfonline.com/doi/full/10.1080/00031305.2018.1543137