Hcg level on 4/14 was 1299 & on 4/16 is 1288. Transvaginal ultrasound on 4/14 showed an irregularly shaped fluid collection in my uterus. Miscarriage?

Missed pregnancy. Hcg should have at least doubled in the 48 hour window. Decreasing HCG signifies a failed, or 'missed' pregnancy. Be sure to follow up with the doctor who ordered your blood test.