Late period

I’m 18 and ttc my first 👶🏽 last month I was late for my period and my cycle ended up being 35 days. I’m now 6 days late today and on my cycle has lasted 37 days. Which is super unusual, it’s never been that long! I haven’t really had any symptoms apart from nipples being really sore, backaches and stomach cramps. I’m too scared to test because we’ve been trying for a while but always get negatives. What should I do? Any chance I could be pregnant 😔