Hard time keeping weight on

So I'm sure I'll get a lot of head shakes for this but.... I'm 32 weeks and have had a hard time eating.. Nothing taste good I'm sick at night and everything seems to give me heartburn/indigestion.... I've lost a few pounds since my checkup 2 weeks ago... Anyone else having a hard time keeping the weight on? I'm at a 23 pound gain and my doctor wants me to gain at least 35-45