New Dad needs advice

Jrv136

We recently found out that my GF is 5 wks pregnant.  She has a 5 year old son from a previous relationship where they decided end the engagement before getting married.  My GF and I have only dated for 7 mths but it has been a fantastic time...My GF her son and I have a fantastic relationship as a family unit together.  We are both in our upper 20's and have good careers so from the start we have talked about wanting to settle down and have a meaningful relationship (which we have) and get married one day.  But since we are already pregnant now it's just been a huge strain....she feels like I would only be marrying her because of the baby, she's stressing about telling our families (given the situation with her first son), she's stressing because we aren't already engaged now.....suffice it to say she is freaking out about the whole situation.....and the crux of the problem centers around this....she doesn't feel like I'm excited about having a baby....I am completely new to all of this...I don't know how the changes in her body are affecting her personality but she is super negative all the time, very irritable, and overall just depressed....I've been trying to help by taking the load off her by doing much more around the house and taking over some of her financial stresses like buying the food etc....BUT NONE OF THAT IS EVEN CLOSE TO HELPING.....any advice I can get about what I can do (esp. little sweet gestures) to demonstrate how much I love her and our baby would be incredibly helpful.  Thank you!!