If I have posted in the wrong section then I will try and get it moved.
I would love the advice of Mumsnet, Google has not been helpful.
The advice is re. Changing a regular bridesmaid dress into a maternity one.
I am 6 months pregnant and I haven't put on any weight anywhere else I am about a 10-12, but my tummy is HUGE, my boobs are bigger too. (It might sound like I look good but I really don't!)
Its my friends wedding in a few weeks (I will of course get bigger by then!) and she has kindly asked me to be the bridesmaid.
She had already bought the dresses for all the bridesmaids so I have to wear it.
Its not an actual bridemaid dress from a bridal shop, she bought them from the high street, it is a floral, sleeveless, quite short, cotton dress. The fabric is quite thin and when I wear it now it goes very short at the front and you can see my pants 
My huge, old knickers are not a good look for a wedding.
She is a dear friend, a lovely girl and in no way a bridezilla and she wants me to wear it and its her special day so I can't buy another one.
I can't afford to pay someone to alter it so the question is how do I change it to a maternity dress myself? She has given me a spare dress of the same size so I can sew the 2 together/use the fabric.
Do is sew in a 'pregnancy panel', I couldn't find anything on google or youtube. Is it even called a pregnancy panel? How do I do this?
How do I let out the sides to fit my boobs and tummy in?
Can I somehow adjust the length to make it suitable?
Sorry to ramble on but I want to make the effort to look nice for her day.
Any advice would be amazing.
Thank you in advance.