Mum Guilt, Anyone?!

So a bit of background, DH and I have two children a 7 year old boy and 5 year old girl. Today I have had a VERY unexpected positive test. The thing is, I am riddled with mum guilt already. I feel like I have one of each and will I love the third child the same, will this negatively affect my children, am I too old (32) to have a baby? ... the list is endless! Has anyone else been in a similar position and have any advice? I was so sure my steretypical family of four with one of each gender was 'it' for me but sooo much guilt and anxiety. Having tried for 3 years for my first and being told it would never happen I know there are millions of amazing people who would love to have just had a BFP but I cant help feeling a bit taken back and uneasy about the whole thing tbh. Any advice greatly appreciated x