Hi. I am a speech therapist. First of all to reiterate what someone else said - you don't have to wait for a health Visitor or GP, you can self-refer to speech therapy - Google your local department and give them a call. Also, do get a referral to audiology as well, just in case. It's always best to get hearing checked even if you're not really concerned about it.
It sounds like your DD has lots of positive communication which is great. She may well be fine, but it's always worth getting a child referred. The main thing is to keep her communicating in whatever way she can - the more she successfully gets her message across, the more she will be willing to try. I understand your concern about signing, but it actually usually has the opposite effect - it takes the pressure off from speaking, which then often means children are more keen to have a go. It also helps them to look at you when you're talking if you're signing too, to focus on particular words and to learn all about conversation, all of which will help. Once children can say more, they naturally drop the signing, but it can be really handy at this stage. Don't worry if you can't find local groups or courses - just use made-up signs or watch Something Special and look at their website.
Other suggestions are - lots of action songs, animal and car noises etc praise any attempt at a word even if it sounds nothing like it, ready steady go games (say ready steady and see if she can fill in go before blowing bubbles, knocking skittles down, rolling a ball - whatever she enjoys). Offer verbal choices - eg do you want milk or orange? Hold both up and to start with she will just point, that's fine, but as you give it to her, say milk (or whichever she has chosen) again for her to hear. Spend a few minutes a day playing 1:1 with her if you are able to - play with whatever she wants to play with and comment on what she's doing with just 1-2 words ( eg teddy...... Teddy sleeping.....wake up etc). Pause lots to give her a chance to talk but don't worry if it takes a while before she does.
Sorry, I've just bombarded you with ideas, but hope at least some of it is helpful! Feel free to private message me if you want to.