It really isn't very easy to tell from the pictures. Her tummy will not look all that big yet if she was covered in August, but then neither should she have a largish udder yet either.
OK can I just refresh things - you got her approx 2-3 weeks ago, her last foal had been weaned a couple of months ago, she was covered once by a stud last August, she was covered by the same stud end March approx this year, she is not a maiden mare. Is that everything?
Right, now to add to my comments above in the first paragraph, can I also ask when she foaled last year - presuming July sometime? Whoever she is in foal to she is not going to foal before July,say, so we have time to get her sorted and watch for the signs that will 'answer' your question.
Firstly, with that udder still looking a bit filled, I doubt that it has been just over two months since her foal was weaned, it looks as though the foal has been drinking from her more recently than that or that udder would have shrunk more - also if foal was born in July, then it would have been approx 6 months old in January. She is going to need some help to get her back into a proper good condition - it looks as though this last foal has really pulled her down, which is exactly what would happen if it was left with her well past weaning time, through the winter months, without her having lots of extra food.
She looks a really sweet little mare and she is as lucky to have found you as you are to have found her. Have you wormed her since you had her and do you know if she is up to dates on all her shots? Then what are you feeding her -does she have access to pasture or is she in a dry lot?
Sorry for all the questions, but she is a nice looking little mare and we just want to help you get her back into a good condition before we start worrying about when she might be foaling - also if she is likely to foal in July, she will need that extra condition to help her growing foal.
Keep the pictures coming - we all love pictures - maybe some of your other horses too?