Son in assessment stage, ASD traits increasing, how can I help him?

Hi, I am new here, looking for advice on how I can help my son please

My son is 7 and a few months back his teacher discussed with us her suspicion that he might be on the spectrum. We were sceptical at first, but as time has gone on, we are more and more convinced that he is.  He’s always been very sensitive, emotionally, he’s socially a little awkward, a somewhat picky eater, and he’s keen on facts and collecting things. He has an obsession with lego, and other obsessions come and go.  Recently, he seems to be changing and we’re not sure if it’s just that we’re looking for signs, or if his traits are genuinely becoming more pronounced. He knows we are working with his teacher to help him manage things he finds difficult, but not about any assessments, as we felt it might change his behaviour if he was aware.

Right now, I am feeling a little lost, and unsure how to help him.  He doesn’t have a diagnosis, so we don’t really know what we’re dealing with, and we don’t have any real support, although school seem to be doing what they can and his teacher regularly talks to us about ways they and we are managing things for him.  His sensory issues seem to be increasing - where before he was a picky eater, he is refusing more and more foods he used to like, always has to have the same brand of the things he will eat, and has said he is ‘scared’ of eating something he doesn’t like.  He now only wants to wear jogging bottoms, as other trousers are uncomfortable and not flexible enough.  The last time he wore a different type of trousers he started screaming and crying, saying that they were hurting him, took them off and wouldn’t put any trousers back on (we didn’t push him to, as it was tea time and we didn’t need to go out) I checked the trousers, there was nothing sharp or rough in them, but the place he said hurt was where the seam was, although I couldnt feel the seam. Since then he has only worn his school uniform and soft jogging bottoms. Labels don’t seem to bother him, but he won’t wear socks when they get a bit old and less stretchy. He’s very reluctant to go out anywhere, and sometimes this will trigger meltdowns - the other day he had a big one because we decided to go out for lunch and to soft play (he eventually calmed down, we went, and he had a fabulous time).  He has developed an aversion to certain words (blood and death, and any words related to them).  Kids at school have noticed and have started saying them to get a reaction. 

 I have a feeling I know the answer, but would like opinions on what to do.  Do we go with it and accept that this is him, or should we try to help him stop things getting worse? He needs new trousers, as he has grown out of a lot of them - do we just get the soft jogging bottoms he favours or try to get him to wear other types sometimes? Do we let him decide what he will and won’t eat, or should we keep pushing him to try new things? My instinct is that we need to pick our battles - so long as he’ll still wear his school uniform the trousers don’t really matter, so I’m happy to go with it, food wise so long as he’s eating something that resembles a balanced diet it doesn’t really matter if he no longer eats peas or bananas.  We do, however, have to go out, and as he has a little sister, he can’t always have his way.  This is one of the hardest things as we are not having much success with managing his meltdowns - we have talked about ways for him to calm himself down, but he goes from nothing to meltdown so quickly, by the time we realise it’s happening it’s too late for anything to help and we just have to ride it out.  With the word thing, we’ve made it clear he can’t avoid them and we will say the words if appropriate to the conversation, but he has come up with ways to deal with it - he spells the words instead of saying them himself, and if he hears them, he says our dog’s name to calm himself down.

does it sound like we are doing ok? Does anyone have any advice on how we can do better?