Long term and serious to not sure what's going on....

This is my first post so I'll try to make this not to lengthy.
I've known my current gf for about 12 years. We lost touch for about 5 or so and then another stretch of time about 3 years, we had just been friends and not very close. We met back up around 13/4 ago and really hit it off, we wanted to take it slow and see were it went. After a few months we were hooked, she's got a now 3 year old son who was 14 months when we started dating. He and I were an immediate fit, his father died in a car accident.

So now about six months into the relationship were talking about buying a house together her son calls me dad my parents papa and grandma, so everythings great then the anniversary of her sons fathers death comes around and things begin to change. She started to distance herself not completely just not emotionally as open. So I took the hint we slowerd down a but took a step back. The. Our work schedules changed, she changed jobs now working full time as a nurse and also working towards her emt certification. We went a few weeks talking everyday in the morning, during lunch's and breaks when on our way to and FTP
Work, and before bed everynight before bed. Id of course talk to her son everyday and so on..... Seemed like just needed to give some time. So a month lot so into this I can't stand the limited time together and begin to say things like I can't do this so on, we took a three week total vreak not talking few texts during important events but not more then that. Last week we began slowly talking again. She came to visit me at my place with her little guy and we had a great afternoon together. At the end of the day when she was leaving I put her son into his car seat she turned gave me a kiss and while hugging me she said I miss you and still
Love you. So she called that night before bed, we chatted for a while had a great conversation. Again today we chatted and she said she'd call before bed.

Ok a little about her to put in this equation, she does not express her feelings very well at least not verbally so during this whole thing I times I've been left with no real answer or reason for some of her actions. Either way it ends up at one point I suspected maybe someone else or that she fell put of love with me. While it didn't ever get to "crazy" with accusations and didn't hurt the relationship that was a period of time, that being said she always told me that she loves me and there's no time for anyone else and I shouldn't even think about that.

Now after the break she did tell me she loves and misses me but that she just doesn't have the time for a serious relationship and with work and eveything she's so stressed and stretched thin. Once again she says there's no one else.

Let me know your thoughts and what you suggest I do and how to go about my next move.