I lost 10 kg in 9 weeks. Healthy or not?

I didnt measure myself the day i started my diet ( 28.1.2019) but i think i was around 83 kg. After that I measured myself on 25.02.2019 and I weight 79 kg. After that I measured myself on 11.3.2019 and I weigh 76kg. On Monday (1st April 2019) I measured myself and I weigh 73.400 kg. I think I am 2.5 kg less that I should currently be. Should I be worried? As far as I know, 10 kg is lost in 12 weeks, but I lost 10 kgs in 9 weeks. I think if I were 76.0 kg today I would be 73.400 kg on 22 April and 22 April is my 12th week of dieting since 28.1.2019. Should I be worried?