I have just sent you an email by private mail with my phone number on it, as I think it would be much easier for us to just have a chat. Believe me, I have been in the exact position you are in, after I first got my tortoise, and I remember being in tears because I was begin given conflicting information and was really losing heart. Honestly, it is something that we can probably solve with a few tweaks, and you won't have to spend lots more money.
Just some quick answers to your questions below:
At 8 months it is almost impossible to tell the sex of a tortoise -- especially Horsfields -- as they tend to look female until they are five or six years old, but sometimes you can hazard a good guess, so if you send us a photo of the undersides of your tortoises, clearly showing the tail, we will have a look.
I had one female tortoise for a long time (lol, she was called Boris when I got her because the man I bought her from swore it was a male tortoise), but then she laid eggs, so her name was changed to Doris). Then I got Dolly, who was definitely female. When I first put them together, Doris -- who is normally a placid, sweet tortoise -- started bullying Dolly terribly. She rammed her shell and bit her and I kept separating them and it just got worse. i was in tears not knowing what to do, but Helen (one of the TTT girls, who bred Dolly), told me that this was natural behaviour as tortoise have to sort out dominance, and as long as they don't draw blood you just have to leave them to it and they will sort it out in a couple of weeks. This involved me leaving the room when Doris was bullying Dolly because I couldn't bear to watch it, but there was no blood drawn and sure enough after two or three weeks that all stopped and ever since they have been two happy little spinsters. One thing that is still odd is that after they come out of hibernation, Dolly (the one who was being bullied), now mounts Doris from the back all the time, as if she were a male and was mating with her. I gather that this can be part of the dominance behaviour and I have heard of other females that do this. It happens every year and Doris doesn't seem to mind. Then after a month or so Doris lays eggs (not fertile of course because they are both female), and then Dolly stops the mating-type mounting and they live really happily together for the rest of the year.
If you want to email me on email@example.com
and give me a time that would be good for you to chat, I'd be happy to give you a call, or you can ring me if you prefer, but I'm sure I will be able to reassure you and we can sort out the problems you've been having.