Worried about my 2 and 1/2 year old speech.?

OK so im worried about my sons speech we had HV round a few weeks ago and she said she would have 2 come back in about 3 months to check his speech i was just wondering is vocab is normal for his age he can say mummy, daddy, nan-nan, he tries to say Jon, Pete and grandad but misses letters he can also say car, toe, mouth (without the th) two, baby, oh no, uh-oh, yeah, knee, head (without a D) bum, what (without a T) he says bitit for biscuit he can say bike, bye, hi, bear, water, ta, ball, fish but he says pish, pop, hat, button, peas, star without the s, wee wee, potty, wow tractor but he says it cacor, for ham he says mam, bus without s, bu for book, na-nah for night-night, yuv yoo for love you and a few more made up words and a lot of baby babble he understands a lot of what i say, he cant count yet just about all of his words are singular and doesn't say sentences do you think this is normal for a 30 month old? if not do you think i should ask for speech therapy?...sorry for all of the above im just a worried mummy lol x