Hi, these are absolutely normal anxieties. I can't really comment on the age bit but all the rest I can say with confidence works itself out. Yes, life is more expensive and busier with each additional child but not doubly so - there will be lots of stuff that you can reuse and if no 2 is a girl, you can keep costs down with clothes from nct sales, charity shops etc. With regards to looking after them, in most cases siblings will play together at some point (although it has taken until my 2nd is 2.5years) which makes looking after them much easier.
Hopefully if you did have another pg it would be easier than the first but I guess you need to be prepared that it might be the same. If in your heart you do want another child, the pg is only a short part of the life you create.
On the flip side, if you really think the obstacles are too big, you need to do what is right for you.
I have a wonderful 15 months old little boy who I love to bits. I work 4 days a week which I enjoy as I can find it quite hard work and so enjoy the break! Husband and I really think we would like to try for another baby but I am so anxious for so many reasons not least of all financial, the extra burden it will bring scares me silly yet I know so many people do it and make it work. I also have all the other anxieties like whether the baby will be ok now I'm 40 and also the fact that I really didn't enjoy pregnancy and had horrible morning sickness, carpal tunnel, swollen ankles, tiredness etc! I also find it hard looking after 1 all day when I do have my time at home with him and so I worry about how I'd cope with 2! I guess I just want reassurance that these are normal anxieties and that it will be ok. I'm so scared of all the negatives but I know in my heart I would love us to be able to have another baby if we can and that the short term might be tough but the long term benefits will be huge. I know people have bigger issues so I'm sorry if this seems silly but its making me really anxious right now as we said we'd try this month but I'm just so worried about everything.