3 year old daughter delayed

Hello everyone,First time posting here and tbh a little unsure of how to proceed being such a tough subject for my wife and I.We have 3 children. 5 year old son and 3 year old twins ( boy and girl, boy elder by 1 minute )For whatever reason our daughter has struggled with speech and pronunciation heavily. She has always been " on her own schedule " as we lovingly call it. Little things like walking later etc but in cases like that the day she chooses to she hopped up and walked albeit 4 months after her twin sibling.We are now close to a year into speech therapy, she's been in daycare for over a year and while I see in her a desire to communicate she seems to fall short on enunciation constantly. Still with very simple things such as " thank you " for example will come out as " tan oo " or " I love you " will be " ah lub oo " and many similar.I also notice when I speak to her and try to push her for a 2 way conversation she tends to just repeat my part which worries me on her level of comprehension. Now... She is very clever when she wants or doesn't want something and finds ways to wrap me around her finger or convince her brothers to ask for X. No clue how she does it but she does.I feel like a year into therapy we should be good with the things that are repeated on a daily basis and working to more complex communication such as multi word sentences etc. Am I wrong?The doctors and therapists have assured us she's not on the spectrum( which if she was I dont care I would just try to accommodate that as needed ) and that it will " fall into place " in time.If anyone has insight into this I thank you deeply. I struggle between feeling the doctors and therapists aren't doing the best they can vs thinking I'm an over concerned parent that's just not knowledgeable on the topic and realistic timelines.TL:DR 3 year old delayed in speech. Docs and therapists say time and therapy will fix. 1 yr in see a desire to communicate but no real advancement.Thank you in advance for any insight via /r/Parenting https://ift.tt/2Hk8j4b