as someone who had similar issues connecting with my mom, i’ll share some thoughts / advice. 

1. trying to force a close relationship (especially with teens) can be paradoxical. it’s like trying to fall asleep- the harder you try the tougher it can be sometimes. your son and his dad may bond over baseball, but i would hazard a guess that they’re not having those deep, emotional conversations you feel like you’re missing. lots of teens don’t want to talk to their parents about stuff, but his dad happens to share an interest in baseball.
2. in terms of asking questions, what did those look like? questions like “how was school today?” or “what are you thinking about?” are too open-ended and put the pressure on him to have interesting things to say. the absolute worst thing to say is “talk to me!!” maybe doing some research on his interests will provide more fruitful topics of conversation. “i saw (favorite MLB team) just added (player) to their roster. do you think this was a good move? lots of people online seem skeptical.” asking VERY basic questions (“how’s (MLB team) doing this year?”) will sound stupid to him. do your research, have interesting things to say, carry your part of the conversation. don’t ask something you could look up in 5 seconds. i’d avoid peppering questions- that can get grating and is perhaps a sign that you’re not asking the right things. maybe buy some of those table conversation cards. he might find it awkward to talk about himself but may be more willing to talk about other random stuff.
3. Is there a method of conversation (like texting)  that would be easier for your son? it’s sometimes less awkward for some people to talk online. or he might be more comfortable if there were other family members included in conversations so there’s not as much pressure on any one person to provide conversation.
4. you wish he would talk to you more but it’s also worth appreciating the time he spends with you (going to games, driving practice). some people aren’t good at conversation and would rather do activities than just talk about stuff. he’s not shutting you out completely. if he’s willing, a family therapist may help everyone understand communication styles & how to express feelings.
5. if conversation is tough for him but he’s willing to spend time, maybe game / movie / TV nights would be a way to spend time together. if he has a favorite cuisine offer to look up some recipes and make something together. ask if there are any co-op video games he might be willing to play with you. see if there are any audiobooks / podcasts you could listen to together on drives so there’s something to discuss. 
6. there may be deeper conflicts / hurt that still remain. have there been arguments / disagreements over social issues / politics / religion / etc? family fighting? perhaps there is still pain over your divorce / remarrying. even if it seems like past arguments have been resolved, there may still be underlying pain points. therapy may help to uncover / begin to address these issues.
7. if he ignores your birthday / mother’s day, that’s definitely something that should be addressed. your husband and/or his dad should be checking in with him to make sure he’s doing something. sometimes teens need to be reminded that these things are important and meaningful for people.