tips to get in the mood

so I'm only 21, i am pregnant with my 3rd child . yes I'm young but I literally have no sex drive and it takes alot to even get me wet down there. my fiance gets frustrated but I cant help it. is there anything I can take or try to do to get me horny? I feel like an old woman going through menopause. my oldest is 3 and I havent had a sex drive ever since having him