ovulated late ?

LMP was April 25, putting me at 7 weeks tomorrow. I got an ultrasound at 6 weeks 2 days and they saw NOTHING, no sac or nothing at all!! The clinic told me I either ovulated late or miscarried. I took a test today and its way darker than the first one I took. Im hoping I see something at tomorrow's ultrasound! 🙏🏼