Don't worry at all. I lost 8 kilos in the first 3 months! I'am now 29 weeks and i am starting to gain a little wait about 2 kilos until now. If your doctor says that the baby's developpement is on track, u dnt have to worry. Many women i know did not gain a lot weight during their pregnancies and their babies were born healthy.
that's what was happening to me also my first dr visit I was 130.6 when I went again I was 131.6 but now idk I got another visit on the 18 since I'm going into my second trimester I should be gaining weight now but you're fine usually lose weight then gain is what my mom told me and my dr told me I was fine Also no worries .
You are fine I was the same in the beginning I was losing and not gaining tell the end I did