feeling guilty

So I have found out in the last few days that I'm 4 weeks and 6 days pregnant, berry shocked as even the doctors were struggling to figure out underlying problems I may have, this is baby number #2 for me, I have a little boy Rueben, who's 3&1/2, it's taken 17months to get to this point and been such a long and stressful journey, from all the stress TTC and also doing everything and anything to help my chances Iv managed to loose quite a lot of weight I'm now 7st8lbs and 4"12 so I think that it's a good/ok weight, im now super in to fitness and eating healthy, I'm over the moon that I'm pregnant but just can't help worrying about the weight gain, Iv felt better about my self for the first time in a long time since loosing the weight 😬, feel so guilty for feeling this way as I know that I'm super lucky to even be having a baby :) and that should be the most important think, any one got any healthy food/meals I could use, and a way of maintaining a good weight through pregnancy?