Could I already be pregnant again after miscarriage?

I had my 1st miscarriage 3 weeks ago. My hubby and I jumped right into trying again a week after because my bleeding had finally stopped. We'd had several times since the miscarriage. And for 3 days I've been extremely tired and emotional also not had a solid bowel movement. Could I be pregnant again already? Should I test already? I've not had my first period after my miscarriage yet.