E.,
I have no idea about the tonsils but I have quite a bit of experience with speech therapy and language delays. My 4.5 y.o. has autism and is language delayed. I don't know where you are but here we have what is called "Nevada Early Intervention" (I'm in Las Vegas and that is what you'd look for in the phone book, or you could get the number from your pediatrician or school district if you have trouble finding it if you are somewhere else). You can self refer (all you have to do is pick up the phone and make an appointment). EI does evaluations and services from birth to age 3. At 3 services are picked up by the local school district. On one had, I don't think it is ever too early to seek services. The further behind a child is, the harder it is to catch up. And most delays are much easier to deal with the earlier you catch them and start services. On the other hand, in my experiences with EI, unless your child is significantly delayed in one area or has delays in more than one area, they won't deal with you so if you go in too early, they turn you away and you have to repeat the process later (irritating! you have to let your child get further behind to get services!). That said, we've used a combo of public services (like EI) and private services (like speech therapy and occupational therapy). I like to tell people to take all the public services you can get because they are usually free and the private services are pricey ($120 an hour for private speech therapy is what I'm currently paying and OT usually runs about $160 an hour). So take everthing free you can get and then work from there. So you can do the EI evaluation and if they turn you away (although I do believe they can opt to give you services even if you don't meet their criteria if your child is "at significant risk of delay" and I think you could argue that), you can always go the private therapy route. EI can also test your son's hearing and since he's got ear tubes, I would recommend that you ask about that.
If your son has any eating/feeding issues those could also be dealt with either through EI, a speech therapist or occupational therapist (some SLPs do feeding issues other times it is under OT, depends on their training and experience).
So the basic answer is that I don't think you are overreacting at all. You've identified the problem and the additional problems it can cause. Why wouldn't you be proactive? By 17-18 months, I knew my first child had some sort of a problem but didn't know what (he's very social which made me rule out autism in my mind without realizing that there is a tremendous amount of variability int he way autism presents itself). Everyone kept telling me to wait, he'd outgrow it. Well, he didn't and we should have sought services earlier and been much more aggressive with therapy. Live and learn.
All that said, another thing that you can do at home to stimulate language development is sign with your child. I have a big collection of www.signingtime.com DVDs and we watch them a lot. I used them a lot with my 4 y.o. and he's often learn the verbal word and the sign at the same time. For him, the visual/tactile representation of the words really helped his verbal skills. He's still language delayed but he's come a really long way and I think sign language was a really important part of helping him. I'm also now signing with my 19 month old (who is so far developmentally normal) and he absolutely loves it. He probably knows 50 verbal words and probably 20 signs. It is tremendously cute, helps him get his point across and really cuts down on the tantrums all while helping his language skills develop. There are absolutely no negatives to signing with your child. The DVDs are kind of pricey though. I'd recommend if you want to try them, start with volumes 1-3. I think those are really sufficient for what most people would do with most kids. I have volumes 1-9 and I like them all. But you don't necessarily have to know all the farm animal signs to communicate LOL! They are just a fun bonus and it helps motivate the kids to learn.
Good luck!
T.