Sex and being pregnant

So . I can't remember when it started happening . If it started before or after I got pregnant. 
He won't or is t intrested in having sex with me?? I've had so many freaking conversations with him . He says its stress . There's been times where he's had trouble "getting it up" while we were trying to have sex !!!!  😡 also I've tried to ask him if it's because of the baby ? Is he worried about that.. He says no . He isn't uncomfortable about me being pregnant and having sex . I know he isn't cheating . I just don't know what to do or think . Tonight was the last straw . I am furious that he hasn't even attempted in idk how long . I know sex isn't everything but come on ladies , it's a huge part of a intimate relationship . It makes me feel so unattractive and ugly . Is it me .. Is anyone else going through this . I feel like everytime we have sex it's only because I'm the one trying . It's gone down to barley 1 time a week if even that . Sometimes it's 3weeks ... It's making me feel so bitter towards him . I know maybe it may be because he's older? I'm 20 , he's 29 going on 30. Any advice please ???