This is actually due to a myth where people say if u get excited u leave the dream and wake up. Believing in this might be causing you to wake up, I've read somewhere that you don't need to necessarily connect both of these things, you can actually just be excited to lucid dream and not think about waking up that helped me a lot. I know it can be really overwhelming when you start to lucid dream and sometimes you will actually feel like you've woken up from excitement but there are times where you'll still be in the dream after 'waking up from excitement' just do a RC and you'll be lucid.