Positive Test!!

Hey guys! Yesterday I was 4 days late. I decided to take a first response pregnancy test with my fmu. The test immediately turned positive within seconds and the test line was much darker than the control line. Can I definitely trust this and know I'm really pregnant? This is my first baby so I wanna make sure its for real since I won't get an ultrasound for 5 more weeks. Any input would be great :)